Yeah, the 7650 is pretty fantastic generally. A lot of people recommend waiting for the Ericsson P800, but to be honest, I've had a good look at it (read the manual etc), and there's no way I would consider paying £500 (expected initial contract price) for it compared to the £150 I paid for my 7650 the day after Carphone Warehouse got them in.
Problems are, as have been mentioned, the camera is a bit blurry (and turns photos annoyingly blue when it takes them), no Bluetooth Audio (this is alleged to not be fixable with software, as it lacks a hardware link between the BT and the audio subsystem, although this may be BS), and the few bugs it has.
Actually, for a Nokia, and a 7xxx series at that, it's surprisingly bug-free. The main issue is that it has a memory protection feature that cuts in to prevent you hitting less than 80k free memory, but if you go below 100k free memory it's no longer possible to do anything with the phone (freeing up memory or even resetting it) and hence you have to take it to a service centre! Other than that, it's pretty good.
Also, there's this guy called Hugo Fiennes that keeps posting on the 7650 newsgroup... Don't know who he is...
A.