I know a lot of people with iphones. I will likely never buy one. Here's why. Note: some of these may be dead-wrong now -- I've heard complaints about all of them.
1) No tethering. You'll likely hear me bitch about this one a lot. I can't use it as a modem. Hell, I can't even use it as a modem to make an ANALOG call, or send a fax. I can't use it as a modem even for relatively-slow gprs.
2) Useless bluetooth. It's good for headsets. That's it. Can't sync via bluetooth. Can't send/recieve contacts last I checked. Can't tether it. Can't transfer files to it. Can't use a bluetooth keyboard. Also: the ipod touch has a bluetooth chip but doesn't support it!
3) Also: Can't sync via wifi -- what the hell? Are you honestly telling me if I buy your sexy macbook air, the ONLY way I can use the ipod with it is by eating the single USB port?
4) No tactile feel. In my pocket, I can blindly feel for the thumbwheel (or even the unlock combination) on my p800. An iphone requires me to be looking dead at it. On the same note, I don't think there's support for a "smart" remote like the early ipods had. A bluetooth keychain remote would also rock. If you know, the bluetooth weren't worthless.
5) No IRDA? Cmon, apple!
6) No voice dialing, tho this is supposedly supported by third-party apps. Apple's such a media-high company that this should be in by default.
7) Is there support for doing calls over WiFi? (and I don't mean with Skype or something third party -- I mean with AT&T, so calls come from YOUR NUMBER and are receivable the same way.) If not, why not?
8) Lack of input options. On my phone, I can get data into it with the numeric pad, use handwriting recognition, tap things out on a tiny qwerty keyboard, use a bluetooth or IRDA keyboard, or connect it to my PC (with a third party app) and type using my PC keyboard. Yes, using the smaller-than-the-iphones onscreen keyboard requires a stylus, but my finger (or a pen) works in a jiffy.
9) The Jail. I shouldn't HAVE TO "break" my phone that I paid lots of money for just to be able to use it. It's already been proven that there's about a dozen ways around apple's DRM -- from tools for "backing up" your ipod, to stripping your AAC files, to "just burn it to a CD then rip it" to the classic "analog hole." Why don't they just make the "jail" turn on ONLY if you are syncing it with an itunes account containing DRM'd music? What this says to me is "you can have bugfixes OR you can have a phone that you can use the way you want, you pick."
10) AT&T's "visual voicemail" should have transcription. Even for an extra fee, this should be a dirt simple drop-in option. And it should give you the option to reply to a (transcribed) voice message via either text, or email.