Yes, I broke down and bought the 8GB iPhone. Here's why I dropped my Treo 700w (Windows) for the iPhone:

1. The Treo was just unreliable. Actually it was probably more the Windows Mobile operating system that was unreliable. Either way, it would reboot for no reason in my back pocket or just not wake up when a call came in. Not acceptable. The iPhone has yet to stop working.
2. Email attachments were useless on the 700w. The iPhone can view nearly anything.
3. Surfing was painful. If the website didn't recognize me as a small screen device, it was next to impossible to view. The iPhone's Safari is just phenomenal here.

So that's why I switched. Here are the reasons I like it even more than the Treo.

1. iTunes anywhere. An update this past weekend now allows me to go to the iTunes store wherever I have WiFi access.
2. A nice 2 megapixel camera.
3. Integration: iPod, phone, camera, email. Can't beat the combination.
4. Conversation-based text messaging. Looks just like instant messaging has looked for years. It's about time.
5. Ringtones can now be made from songs you've purchased. (for another 99 cents, of course)
6. Outstanding photo albums synched with my PC. Now I always have pictures of my two daughters with me!

Now the downsides (your mileage may vary):

1. There is no way to mark all emails as read. Since it does not recognize that I have read my emails on my Outlook/PC, once I leave the house I have to "read" each email so that my new email messages equal zero.
2. Third-party applications! This is probably the biggest complaint on the net right now about the iPhone. Only Apple can put an application on your phone. So I lost two applications with the switch. But it was still worth it.
3. That nice camera does not capture video like most camera phones. Bummer.
4. AT&T's network just doesn't have the coverage of Verizon Wireless'. I hope I don't regret the change.

I have heard other reasons not to get the iPhone like incompatibilities with the Exchange server, but those other reasons didn't concern me. That's why this is a biased and unscientific review of the iPhone.