iPhone 4 here ... no complaints, not even the signal-loss. Battery life is pretty good, unless you download 'Angry Birds', then kiss battery life good-bye
Apps are much faster than on previous models. Both cameras are great! The outside HD camera quality is incredible. The VGA front-facing camera is very useful for self photos, and for FaceTime*.
* - Sucks FaceTime is wiFi only, unless you use My3G when you jailbreak the phone
or else use Fring to do video chat with Skype, AIM, MSN, Yahoo, etc..