I did a clean install of iOS 7 on my 4S and barely installed any apps. I have just been using iMessage via Wifi for a while and I realized that the battery was drained way too fast. The battery life was very nice when I was using iOS 6. Other than batter life problem, everything seems fine so far. My 4S is not slow at all like what I expected. Does anybody also have battery life problem when using iOS 7 on 4S?