My battery life has been absolutely terrible ever since I updated my iPhone 5 to iOS 6.0.1.  Tonight I discovered it was because the brightness setting was set to the maximum after  the update.  Thinking this might’ve been some sort of fluke I checked my wife’s iPhone 4.  Sure enough the brightness setting was maxed on hers too.  If you’ve been having battery issues since the update you might want to double check this setting.