i have an iPhone, and it has not missed a beat...
like i convinced mitch to do with his.... the first thing u need to do is hack it tho... only a muppet would pay for applications, after its hacked, its a whole new toy.
you can load in new themes, put on applications that apple did not want ppl to have (like sharing the 3G connection with a laptop, and the ability to record video for instance).
everything is easy to use if u dont have fat fingers.
if u get one, first stop is whirlpool.com, you will get easy to follow instruction on how to hack (jailbreak) and heaps of awesome applications. (like stumbler plus, and spoof mac. with these and a wee bit of know how you can get into "secure" wifi networks).
i dont regret getting it at all, im with optus on the $129plan, i get 3Gig of internet, and unlimited calls n texts