If you are still wondering whether to make an iOS upgrade to latest 4.3 version, then this piece of information may be useful for your decision. Just recently, there are many forumers complaining that their iOS devices’ battery life has deteriorated quite significantly after upgrading to iOS 4.3.
According to those affected users, the previous battery optimization methods of either turning off push notification services, WiFi, Bluetooth and even Location Services do not able to remedy the severe battery drain issue as claimed by users. And so coincidentally, the battery issue happens after those users upgrade their iOS devices to latest 4.3 version. While most of them doesn’t specify the details, some users did report that the poor battery life could be due to the auto screen lock issue that makes the screen backlight to stay on for long hour, and eventually drain the battery faster than normal.
Currently the battery drain issue only impacts iPhone 3GS, 4 and iPod touch 4G only and good thing is, there seems to be a temporary workaround as some users have successfully eliminated the battery drain issue by doing a full device restore (not from previous backup copy). However, there isn’t any acknowledgment from Apple Inc yet so do try out yourself if this helps resolving your battery drain issue.