I don't really want to spend over £400 on a phone to then lose money by selling it on in case I don't like it. I haven't used any of the latest Android phones, only an old HTC Desire, so I don't really have anything to compare my 4S to. I do like the way you can customise Android over iOS, but I would miss the simplicity and build quality of the iPhone. Another thing I'd miss is that I plug my iPhone into my car for music and long journeys, I use iTunes for my music library so I guess I'd have to buy a separate iPod for that.
If I do order one, I take it go for the 16GB version and buy a larger and quicker SD card rather than spending more on the initial outlay?