A couple thoughts after flipping through the iPhone web pages and whatnot:

Speed / battery life. The claimed improvements are less than I was expecting, but still appear quite impressive.

Price. Apple hasn't announced all of the terms of the deal, but if it's a standard two-year lock-in or something similar, it's a reasonable deal for what you're getting.

Bluetooth A2DP. Not an announced feature. Unclear whether or not it will become one. Boo on Apple if they leave it behind.

Depth of dev support. The litmus test is whether Skype can implement a first-class client that runs over AT&T's data network. Without that, I'm not impressed. Presumably, we'll at least be able to get text Jabber support.

Sync. I have this fantasy that, on every web browser, or using local apps on the phone or whatever, everything stays synchronized properly: contacts, calendar, mail. Right now, Apple seems to be saying "you can have this if you've got an Exchange shop, or if you buy into MobileMe." I, of course, want it from Google. Others will want it from Yahoo. I suppose I could always wait for an Android phone, but heaven only knows how long that will take to become real.

(Incidentally, since Google continues to fail to offer decent to-do list management, I've gotten sucked into RememberTheMilk.com, which happens to have a brilliant Firefox plugin that renders a new column on the right of your Gmail, nicely integrating to-do management with everything else.)