I've heard a lot of complaints about corporate users not wanting the iPhone... the lack of Exchange support, the lack of IMAP idle, not being able to sync calendar and contacts over the air, etc. Perhaps I'm unique, but I've been a very happy corporate user thus far. Granted, I don't use an Exchange server. I use a regular ISP that supports IMAP and POP. And I was already used to sync'ing to get my contacts and calendar (granted, with my Treo that was via BT). But needing to sync via cable isn't that much of an issue for me as the included dock just sits next to my computer. Besides, the SDK is around the corner which means pretty soon I'll be able to do what I've always done with my Treo: buy some good, stable, third party apps that I'm sure will open up all sorts of options for me including IMAP idle, Notes syncing, and perhaps even syncing my contacts and calendar OTA.
I've been using my iPhone for a week now and its been great. My Treo 680 had served me well (as had my 650 and 600), but it was older and getting a bit marred. Plus, there is some uncertainty about the future of Palm. Don't get me wrong, I wish Palm the best and could very well switch back to a Palm device someday in the future. But for now, the iPhone represents the best of what's new and cutting edge and seems to be a great tool for a first generation device.