I loved my iPhone4, but it's failure to get the basics right made me jump ship. I was dropping every other call, putting people on mute, hanging up on people, randomly dialing numbers in the middle of a conversation, starting 3 way calls with people and so on...
At the end of the day it is a phone and it needs to be able to make and hold phone calls. I was not able to do that and when you use it for business calls it becomes a big mess. This is a combination of crappy AT&T service and a phone that should have been held back from releasing for another couple months. When I returned my iPhone there were 5 or 6 other people in line returning them as well.
All the other features of the iPhone 4 were amazing, I can't complain about that. The battery life, the hd screen, the video, the pictures, the apps, the front facing camera, no complaints.
After doing a lot of research on the android platform these last couple of weeks I can not wait to get my X and start customizing.