When the iPhone 4S launched by the apple, the iPhone lovers have complained about the poor performance of battery and instead of this Apple's claim iPhone 4S' battery life was worse than iPhone 4.
Now the Apple released iOS 5.0.1, according to Apple officials the bugs are fixed which effect the battery life. But the user of iPhons 4S not satisfied, it didn’t fix the issue and some case users (not just iPhone 4S users) complained that they started observing the issue only after upgrading to iOS 5.0.1.
Apple accept that it may have not fixed all the bugs affecting battery life and will clear in a future iOS software updated. So as promised (though after quite a long time), Apple released iOS 5.1 yesterday, which according to the iOS 5.1 release notesalso addresses bugs that affects battery life.