If you haven't noticed, Spotify just updated and changed its interface in a big and rather good way. You'll see a fresher, cleaner interface with a predominantly black theme going on. There've also been tweaks to the fonts, and while the basic design is the same, you'll see that Spotify has polished the overall look, with a more generous use of stylised icons.
The designer seems to have gone crazy with the opacity slider though, as most of the background images used are semi-translucent. Not a bad look, honestly, and you might notice the app loads slightly faster perhaps due to better image size optimisation.
Your Spotify apps still work as they used to, but you'll be most pleased by two new additions: the 'Your Music' feature and tweaks to how 'Browse' works.
No time for playlists? No problem
There are days where you like a particular song and want to set it aside, but adding it to a playlist seems too much work. Spotify anticipates that by creating a Your Music section where you can tag an album or specific track so you can get back to it later.
The Browse feature will now no longer be static, changing recommendations according to the time or specific day. It's a Monday morning? Then Spotify will offer some commute-friendly music, or offer a party jam for those Friday evenings.
New users will automatically see the new look while those who don't see it yet, patience. It'll come your way soon-ish.