It has been assumed that the purpose of iOS 6.0.2 was to fix a bug reported by iPhone 5 users who say their devices aren't staying connected to WiFi, and fall back to cellular data networks, using large amounts of data. Now, the guess is that the fix to this bug is the cause behind various reports from users seeing their batteries drain faster than normal.
Not a lot of people have been reporting battery drain issues, so it's unclear how widespread the problem is. No statement from Apple about the claims. iOS isn't alone though. Word has it that Android 4.2 is causing battery drain, and Google hasn't made a statement about that either.
source: Ars Technica