I actually own an iPhone4
Just got mine this week, and I've got a few observations to share:
The antennae issue, is of course, a non-issue. Not too many surprises there.
Reception and 3G signal strength is miles better, but I'm mostly putting this down to having switched from the god-awful O2 to Orange. Actually having a 3G signal sitting here at my desk feels like a revelation, much to the amusement of my work colleagues who've always had it on other networks.
The phone looks and feels amazing.
And, er, that's about it. It's an iPhone, but much nicer than the old ones.
It's probably mostly down to the O2 to Orange switch but I'm much more satisfied with this handset than my old 3G.