Friend of mine upgraded to a 3G iPhone. Quickly became evident that the 3G access was just crap. He could barely get one bar on the strength meter, even when close to a O2 mast. To do anything with it, he had to turn off the 3G and rely on EDGE.
Now whether that's because the iPhone has crap 3G reception, or whether it's O2's 3G coverage that's crap here (Nottingham), we don't know. But whatever, it was pointless upgrading.
However, he still came out of it okay as he decided to keep his old iPhone, and sell the new one on eBay for 400 quid. Which was fine by him cos the old one 'feels' nicer anyway.
It's all made me think twice about whether I want one.