I bought an iPhone 4S 16GB (White) as a Christmas present to myself last week, upgrading from an iPhone 4 16GB. So far I'm liking the speed difference in certain apps and while Siri is a bit of a gimmick at the moment, it's fun to play around with. The battery life is about the same but I've been stuck with the dreaded "Searching..." and "No Service" two or three times when coming out of a bad service area, usually sorts itself out after 5 mins or so but I'm having far fewer dropped calls than on my iPhone 4 which is a huge bonus. So all in all, not sure it was worth £500 SIM Free but it's a damned sight better than the Nokia Lumia 800 I bought before the 4S!
Got a foofbag coming for my iPad 2 and 4S early in the new year