I just got one of these yesterday (friend brought it back for me from Thailand, but it's originally an imported US one, even came with the AT&T sim).
Really interesting to read all the negative comments in this thread - I can only assume that none of you have actually used one of these, cause it is hands down the most incredible piece of technology I've ever used. It's just amazing. I've mostly been using it for internet surfing (on wifi) which is really good.
Also, if you have an unlocked jailbroken one (like me) it really addresses a lot of the problems people have with it, i.e. there are shitloads of third party apps that you can download for it & there's now faux GPS using cell phone towers integrated into Google maps (which actually works pretty well i.e. within 500m). You can also convert your mp3s into ringtones for free, it's a bit fiddly but you can do it using nothing but iTunes.
The main great thing about the unlocked ones, is that it only cost me $644AU, and I'm using it on Optus in Australia on my crappy $9 a month plan. That was the main thing that sold me on buying an unlocked one vs waiting (endlessly) for Apple to actually release it in AU. By the time it gets here it'll be on some ridiculously expensive plan which I'd also no doubt have to switch providers for.
So yeah, it's great
