Should you upgrade to an iPhone 4S?
OS and Siri
iPhone 4: One of the great sells of an iPhone is the promise of prompt OS updates and the iPhone 4 is due an iOS 5 upgrade to replace its fraying iOS 4. That'll come, but without the voice-controlled HAL-esque AI of Siri. If you don't want Apple knowing your mum's number, you just keep that iPhone 4 in your pocket. (We should point out, out of responsibility, that simply having Siri doesn't guarantee Apple access to your family tree.)
iPhone 4S: Alas, to take full advantage of all iOS 5 has to offer, you'll want the 4S – Twitter integration, notifications, iCloud, the BBM-alike iMessage and, of course, Siri, the voice control feature which won't run on the iPhone 4's single-core processor. After our hands-on with Siri, we think having pleasant conversations with our iPhone 4S could seriously be worth the upgrade – if you don't mind dictating texts, appointments and asking for directions out loud that is.