The thing that worries me is that it's slower than iOS 6. Look at iOS 6 on the iPhone 4 and you will see it's very slow compared to when it came out with iOS 4. It worries me that this gradual slow down as we upgrade to a newer OS may be happening after just one software update on the iPhone 5, which was a beast on iOS 6.
Another thing that annoys me about iOS 7 are the longer animations during which you can't tap anything.
Overal I really like iOS 7 and it would be perfect if it can run as smooth as iOS 6. The visuals are much cleaner and more precise (although I do get nostalgic for iOS 6 graphics once in a while because they are so much more tappable and fun-looking.
Another thing that annoys me about iOS 7 are the longer animations during which you can't tap anything.
Overal I really like iOS 7 and it would be perfect if it can run as smooth as iOS 6. The visuals are much cleaner and more precise (although I do get nostalgic for iOS 6 graphics once in a while because they are so much more tappable and fun-looking.