Been using them at work and been very dissapointed.
There big (not ideal pocket size by any means)
The camera is still crap
Battery life is awful (was getting about 1.5 hours when used as a satnav)
They crash way to often (try fast tapping the screen)
Not as user friendly as you might think, typing stuff is a night mare!
The receiver is pretty poor
All in its yet another gimeky apple product with a fancy user interface that fails to do the basics well.
To big? - Get bigger pockets
- Its same size as the iPod Classic/Touch, that fits in my pocket fine.
Camera is usable - A phone will never be a camera anyway
Battery, considing size of screen and features it lasts ok, better than some Nokia's!
Typing - Its just practice, 1 way around, press and hold, and slide your finger up and down, to the key, then release, rather than just tap. Like anything practice, and you get better 
To get better signal, move south! 
my SE K850i begs to differ (even though i actualy think my old K800i was better!) 
Got several K850i's here, still not great.
remember phone companies keep showing off more and more mega pixels in the camera phones, but they are still on the same size CCD, you get greater colour spill the more pixels they try and cram in.
Higher megapixel, does not mean better images!