It's been a bit over a month now, and I have to say that I love my iPhone. It's small--thinner than a Motorola Q, which I think used to be the thinnest smartphone on the market--and lightweight. It works a lot better than my Treo 650, even though the virtual keyboard took a little getting used to. I find that I'm using my mobile email a lot more often than on my Treo, probably because of my iPhone's ability to work well with IMAP folders. The iPod and phone features all work very well.
Much to a co-workers chagrin, the transfer of my phone number to my iPhone from Sprint, including the activation process, took all of 8 minutes. Smoothest phone activation that I've experienced.
Problems have been minimal so far. Aside from the obvious things that are left out (including copy and paste), it does crash sometimes when loading a particularly large webpage. Not enough to worry me though: I'm certain that Apple will continue to release software updates to resolve most of these issues. I find the speaker phone to be quite weak as well. I also dropped the darn thing down a metal staircase within a couple of days (clanging down all 12 stairs!), but it still works well, with nothing but a superficial scratch on the aluminum case. .
I'm now on the quest for accessories. And I know what I want for my birthday (hint): a wood case for my iPhone. In Padouk please.