I've been using the iPhone 4 on AT&T for over a year now, and it has been an exceptional experience. The design of the iPhone 4 is pristine, the issue come due to it's fragile glass construction, I have not cracked the screen, but I still worry every time I drop it, using aluminum would have been a better choice. The screen is the best on any phone I have used, save for maybe the Galaxy Nexus. The camera on the iPhone 4 is good, but not nearly as good as the iPhone 4S. The front camera is really crappy, I flip the phone over and use the rear camera if I want to take any self-portraits that don't look like absolute garbage. Reception–I've never had much of an issue with this, I have only dropped about three calls over the past year. The performance is great, I don't see lag anywhere. iOS 5 is really good, although a bit warmed over and boring, other than that though, it is extremely well designed and thought out as you would expect from Apple. I get about a day and a half of battery life on the weekdays and a day on the weekends. As far as the ecosystem goes, I have never not been able to find a given app on the App Store that I needed, so I'm not left desiring anything here. Overall, the iPhone 4 is still a great phone an it has been a pleasure to use it. I am looking forward to buying the 2012 iPhone, which I hope will have a slightly larger screen with a refreshed design and software.