Well, I have an IPhone 3GS, and it's given me a multitude of problems. I think I'll make a short list.
Now, I hate AT&T, They have shitty service in my area (Northeast Ohio), and horrible customer service. But now with the list of fuck-ups.
The power button doesn't always work.
It freezes when turning on. (But it's an apple product, so I expect that.)
It somehow thinks when I'm on one app, be it MSN to a game, it thinks I want to be on another app, and switches me to it. Isn't that dandy?
When connected to the bluetooth in my car, it likes to randomly dial numbers from the phone book for me. AT&T says it's the car, dealer says it's the phone.
Sometimes when I'm trying to start a text message, the keyboard doesn't pop-up, and I have to try multiple times to get it to work.
That's about it. I'm about to just buy out of my contract and shoot an arrow at the thing.