However, even though a majority of the users are reporting an improvement in battery life (while some saying they never had any issues to begin with) there are a certain number of users who are still complaining about poor battery life post-update. When AllThingsD wrote about this issue, Apple responded to them with the following statement.
“The recent iOS software update addressed many of the battery issues that some customers experienced on their iOS 5 devices. We continue to investigate a few remaining issues.”
It's clear Apple wants to leave no stone unturned and wants to take care of this issue once and for all. You can probably expect another update soon that should take care of the remaining battery life issues on your iOS device, if any.