It’s not often we get to see a whole new set of barriers broken in the mobile world these days. Phones have already destroyed most of them. Heck, they’re already more powerful than some of the laptops we used just a few years ago.

The Sony Xperia Z5 Premium manages it, though. This is the first phone with a 4K screen. Some people say 4K TVs are pointless. What about 4K phones?

Unless you’re buying the phone for bragging rights, don’t put too much faith in the screen. It’s as silly as it sounds. However, this is still a good handset in its own right, especially if you don’t mind the eye-clawing £630 price.

Would we pick it over the Samsung Galaxy S6 Edge+? In a word, no.

Glass on Metal on Glass

The Sony Xperia Z5 Premium is an enlarged version of the Xperia Z5. This introduces a problem, though.

Sony’s Xperia phones have boxy bodies, and it tends to make them feel even bigger than they are, compared to a curvier alternative. With a 5.2in phone like the Xperia Z5, that’s not a killer issue. But with the 5.5in Z5 Premium I do think it’s enough to put a few of you off.

I find it more of a handful than the Samsung Galaxy S6 Edge+, even though the Samsung has an even larger screen. It’s a brute among 5.5in phones.

The lip of the seam that joins the sides to the back is also a bit sharp. It may sound like I’m nit-picking here, but this all adds up to a phone that doesn’t handle as well as most of the phones the Xperia Z5 Premium competes with.

It’s made of pretty fancy stuff, though. The front and back panels of the Sony Xperia Z5 Premium are Gorilla Glass, the sides gloss black-coated metal. It feels cool and hard, telling you pretty clearly that it costs big bucks. It feels significantly more flash than an LG G4.

Only the little corner bungs are plastic. This is so that when/if you accidentally drop it on the pavement, they’ll just deform a bit rather than directing the pressure inwards, shattering the screen or back. That would be bad.

King of the compacts

Sony specials

Unlike a lot of top-end phones, the Sony Xperia Z5 Premium has a microSD slot too. It lives alongside the nanoSIM space in a plastic insert that slots into one side of the phone. There’s already 32GB on-board too.

The other bit that remains a real Sony draw is waterproofing. In recent months Sony has gone from saying you can dunk its Xperia phones as much as you like to recommending you don’t submerge them in water. It’s a bummer, but nothing has really changed. The Sony Xperia Z5 Premium is still pretty much totally waterproof, Sony has just realised that tiny little rubber seals aren’t invincible. Sensible move.

The other bit I can’t go without mentioning is the fingerprint scanner. It’s exactly the same as the one on the Xperia Z5 and Z5 Compact. It’s a fast, accurate scanner, and sits on the right side of the phone. Having used phones with front, rear and side finger scanners at the front, I’m sad to report that the side kind is probably my least favourite positioning for this tech.

It makes you move your screen-prodding thumb further away from the display than the other types, making it feel that bit less immediate. That said, plenty of people think the Sony Xperia Z5 Premium scanner is the nuts. It think it’s good, but I prefer the ones on the Nexus 6P and Samsung Galaxy S6 Edge+, slightly.

Next-Gen LCD

It’s the screen that really sets the Sony Xperia Z5 Premium apart, though. And here is where things get complicated.

The Sony Xperia Z5 Premium has a 5.5in 3840 x 2160 pixel screen. That’s over eight million pixels in total, which, for a phone, is clearly mad. If we’re going to be really picky, this is a UHD screen rather than a 4K one - basically, it has a slight lower resolution than what's officially deemed to be 4K.

Let’s stick with calling this screen '4K' for now. Everyone else is.

What makes the phone contentious other than that your eyes can’t really tell the difference between a 518ppi screen and an 806ppi screen like this is that the Sony Xperia Z5 Premium doesn’t always display at 4K. The pixels may light up, but most of the time the images being driven to them are 1080p. So what that means is four of the Premium’s pixels will be displaying the same stuff: 1080p has a quarter the number of pixels as 4K.

The result is that if you get your eyeball right up against the screen, it looks a teeny, tiny bit soft compared to the LG G4. However, after five minute of peering at the thing, I sat back thinking “ what am I doing? This is ridiculous”. It’s a very sharp screen. It looks great.

So when is it “proper 4K”? When you look at images or 4K video. What this means in reality, most likely, is when you look at your photos. While there’s loads of 4K content on YouTube, the YouTube app only lets you select up to 1080p because the app itself is only running at 1080p.

The same will stand for Netflix and so on. Even Sony’s own video store only lets you buy 1080p HD movies on the Sony Xperia Z5 Premium. There’s a good reason for this, high-quality HD movies take up a lot of data. 4K ones take up mountains of the stuff.

Back to the real screen

Although the whole 4K resolution screen thing is silly, the Sony Xperia Z5 Premium’s display is great in other respects. For an LCD blacks are deep and the colours are vivid and punchy while still maintaining a good separation between shades that are meant to really pop and those that are meant to be a bit pastelly.

Sony’s clearly put a lot of work into calibration, even if you don’t get the option to have muted ultra-natural-looking tones, as in the Samsung Galaxy S6 Edge+.

As in so many other Xperia phones, the white balance is set to be a bit cool/blue as standard, because this is what gets you the perception of highest brightness. However, you can tweak this with the RGB sliders in the Settings menu. It’s a real unfriendly way to let you tweak out this cool slant, but it works.

Being an LCD, angled brightness and black level can’t touch OLED phones like the Nexus 6P or the Samsung Galaxy S6 crew. But for an LCD it’s pretty damn good.

The Sony Xperia Z5 Premium will make a pretty great media phone. However, the speakers are starting to lag behind pretty clearly.

The phone has a pair of front speakers, one at the bottom one at the top. This gets you a nice attempt at stereo when you hold the phone on its side. However, for such a big phone the Sony Xperia Z5 Premium has a pretty thin tone. I used it side-by-side with the S6 Edge+ and the Samsung has a lot more body to it. And the HTC BoomSound phones have a bit more bulk still.

Sony suit

There’s also not all that much movement on the software side. The Sony Xperia Z5 Premium runs Android 5.1 and the same custom Sony UI you'll find on the other Z5 phones. It’s simple, it’s clean. It runs like a dream (for the most part).

But it’s also a bit sharp and stiff-looking, just in the way it draws its custom app icons. There are shades of “city boy” here, and at times you’d wish it’d ease up and stop wearing its pinstripe suit to yoga class. I still much prefer it to what LG ships out in the LG G4, mind.

The real strong bit is snappy performance. But then would you expect anything less from a £620 phone? The Android Marshmallow Nexus 6P is quicker still, and I noticed a very occasional micro-second pause when flicking through the settings menu once, but it’s on-par with the S6 Edge+.

Under the surface, the Sony Xperia Z5 Premium has the same Snapdragon 810 CPU as the regular Z5 and the Z5 Compact.

While Sony says that its use of 1080p resolution most of the time is to save battery, it also makes sure there aren’t any performance issues that are down to having to render those extra, ooh, six million pixels. 95 per cent of the time this is a 1080p phone, so 95 per cent of the time it pretty much is just a blown up Xperia Z5.

In Geekbench 3 the phone scores 4245 points, just as expected. It has exactly the same power on tap as its brothers.

Mighty mobile

4K crisis

If the Sony Xperia Z5 Premium ever acted like a 4K phone, trying to get games to run at 4K, for example, we’d perhaps get to really see what the Snapdragon 810 can do. But really it’s just business as usual: pretty much everything runs at 1080p, so everything’s going to run just great. Sony also seems to have worked on the overheating issue of the Xperia Z5. I found the Premium doesn’t get quite as hot anywhere near as quickly.

I’m not praying for a disaster here, but the more you think about it, the more the whole ‘4K’ spin for the the Sony Xperia Z5 Premium seems like a bit of a misdirection. There is one part of me that does wish this was a true 4K phone, though. It’s the part that has tried on a whole bunch of those mobile phone slot-in VR headsets and found the image to be pretty blocky, spoiling the immersion.

An 806ppi display would make phone VR look amazing. But right now the Sony Xperia Z5 Premium can’t pull anything like that off. In theory it’s possible, though. The Snapdragon 810 already supports 4K displays. It’s not as though Sony has had to pull off some David Blaine software magic just to get the few 4K-compatible bits working.

It wants to sell itself as a cut above everything else out there, but the Sony Xperia Z5 Premium is ultimately very familiar.

No Nightcrawler

There’s nothing new in its camera either. The phone has the same setup as its brothers. That’s a 23-megapixel main camera with an LED flash and a 5-megapixel selfie camera.

Many people have gushed about the Sony Xperia Z5 Premium camera. And it’s good. However, having spent a whole lot of time with it, first in the Z5, then the Z5 Compact and now here, I really don’t think it’s up there with the very best.

But let’s start with the good stuff. In daylight the Sony Xperia Z5 Premium can take some great shots. Not only does the main sensor have an ultra-high resolution 23-megapixel sensor, it’s a large 1/2.3in one too. That’s larger than the sensor of some dedicated compacts (if not particularly great ones).

It also has a decent default ‘no brainer’ mode that selects shooting styles, including the HDR-a-like ‘backlight’ when needed.

During my testing of the Xperia Z5 Premium, though, I got to use it alongside almost all of its big rivals: the iPhone 6S Plus, the Nexus 6P and the Samsung Galaxy S6+. And it simply came up short on too many occasions.

First, there’s speed. The Xperia Z5 Premium is the slowest-to-shoot of all those phones, in part because it always focuses after you’ve pressed the shutter button. In effect there’s a half-second shutter lag even though it has speedy phase detection autofocus. Next to the lightning fast Nexus 6P, it feels downright lazy. The Z5 tries to hide this behind a focus sound just like the one made by cameras like the Sony RX100 IV. But I’m not fooled. It’s also slows down more than key rivals at night, which is a shame.

Next up there’s low-light performance. From a distance, the Sony Xperia Z5 Premium can seem great. It’s able to brighten-up even near-black scenes using incredibly high ISO settings and massive amounts of smart processing. It’s impressive stuff: no phone can shoot a dark room like an Xperia.

However, the actual image quality of low-light photos is actually pretty poor. I shot a night scene using the Sony Xperia Z5 Premium, the Edge+, the iPhone S6 Plus and the Nexus 6P, and the Sony had by some distance the poorest detail.

It doesn’t have the optical image stabilisation of the Apple/Samsung phones or the large sensor pixels of the Nexus 6P. And so it’s stuck just whacking up the camera’s ISO sensitivity, which is the root of why photos get noisier when it’s darker out.

The bit I find funny here is that even as I’m doing down the Sony Xperia Z5 Premium’s camera get-up, Sony also makes the sensors used in the Nexus 6P and the Samsung Galaxy S6 family (which reportedly uses a mix of Sony IMX240s and Samsung-made camera brains). They’re different parts of Sony’s business, but they share a logo after all.

On the sort-of positive side, the Sony Xperia Z5 Premium still has all the bonus modes and AR fun you get with the other Z5 phones. The highlight is being able to wrap 3D models of other people’s and animals’ faces onto your own. They move in real-time along with your mug, in a quite disconcerting way. It’s more 6-year-old’s birthday party than Face/Off, but at least it’s different.

Super snapper

How long can you last?

Where the Xperia series seems to have lost its cutting-edge feel is battery life. It has a big-sounding 3430mAh battery offering you better stamina than the LG G4, but I find that both the old Xperia Z phones and the Samsung Galaxy S6 Edge+ last longer in most scenarios.

You’re looking at a solid day and a bit off a charge. But not the two days that sizeable battery may seem to promise.

Our regular video battery drain test, where we play a 720p movie on loop, showed a very disappointing result of just nine hours. Older Sony phones used to do much better than this. Maybe Sony’s not saving as much battery by using 1080p instead of 4K resolution as it hopes.

The phone supports super-fast charging, which is a great extra that’ll whack up the level to 80 per cent in an hour. However, we couldn’t get hold of one of the Premium’s fast chargers, so we’ll have to take Sony’s word for it on that one.

Sony Xperia Z5 Premium verdict

The Sony Xperia Z5 Premium is the emperor’s new clothes of 2015 phones. Its biggest selling point, having a 4K screen, is pretty pointless. Not necessarily because your eyes can’t see the difference, but because barely anything runs at 4K. Otherwise this could have been the ultimate VR phone.

As it is, the Z5 Premium is a very good large-screen phone, but one that doesn’t quite match up to rivals like the Nexus 6P, Samsung Galaxy S6 Edge+ and iPhone 6S Plus. It pulls the same Top Trumps game with its camera too: 23 megapixels sounds great, but alternatives are both faster and better performers at night time.

Handy waterproofing, fancy feel and a good finger scanner are all solid notes on its record. But unless you really dig Sony’s style, the screen resolution isn’t enough to put the Sony Xperia Z5 Premium at the top of the tree.

Tech Specs 
Screen
5.5in Ultra HD LCD
Software
Android 5.1 with Custom Sony UI
CPU
Snapdragon 810 octa-core 2GHz
RAM
3GB
Storage
32GB with microSD
Camera
23-megapixel with LED flash rear and 5-megapixel front
Battery
3430mAh
Stuff says... 

Sony Xperia Z5 Premium review

Big, powerful and certainly ‘Premium’, but it’s not a Samsung-killer.
£599
Good Stuff 
Feels expensive
Handy waterproofing
High-quality screen
Bad Stuff 
Quite bulky
Most rivals have better low-light photo quality
4K display is largely meaningless

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