Well, this battery drain issue is coming from iOS 6.1 to me and it seems that it is common on almost every iPhone model (4, 4S, 5, etc). It maybe not the iOS itself, perhaps from this version, the iOS gives some opportunity to some Apps to do some stuff in the background that kills battery. Some of us have this kind of apps and having battery problem, other don’t.
My iPhone battery was good prior to iOS 6.1, with 5 hours of usage and even up to 5 days on standby! After upgrade to 6.1, it loses 2~3% battery every hour on standby and only lasts for 1 or 2 hours of usage before dead. It is not as bad as some who lose 10% of battery every hour on standby, but to me, the battery life has reduced to one quarter of past.
I am sure Apple is working on it and iOS 6.1.2 seems to be an urgent upgrade to solve, but I knew it won't solve my problem, because I don’t use the Exchange account and the update aimed to solve that issue.
I think the best solution is that the Apple gives us the choice to downgrade to iOS 6.0 until the next stable version is ready to go. This solution will give the Apple the time to find and solve the problem and gives us our phones back to use.
View the Correct Answer Apple let us downgrade to iOS 6.0 in Solve the iphone problem , iPhone 4S problem Correct Answer