I have 4.something. The reason why I have not upgraded is 4 reasons. 1) I'm over clocked, so I'm running supper fast. 2) I have speed intensifier, which is truly a joy. Everything appears to be lightning fast. 3) Still have good enough battery life - enough for the day. 4) Can't risk losing my jailbreak. Right now my iPhones running extremely stable and smooth. I have no complaints simply bc my iPhone's running incredibly fast - must faster than the 4S, AND smooth (no lag, crashes, freeze, etc) Love love love it right now & dont want to risk anything.