I got this tip off of another forum here, it might work for you. I restored my new iPhone 5 from a backup of my iPhone 4S. After two weeks, I noticed that I wasn't really noticing a huge improvement in battery life -- the phone was basically on the same charging schedule as my 4S.
I read a thread here that said the battery charge settings have been known to carry over from the backup of a previous phone model to the new phone, and that the poster had seen a dramatic increase in battery life after he did a "Reset All Settings" on his phone. I figured it couldn't hurt, so I tried it (about two hours ago).
Before the reset, my phone would drop 2% from 100 to 98 within a few minutes of being removed from the charger. Since I reset the phone a few hours ago, the phone didn't hit 98% until after about an hour of moderate use (downloaded a 50 minute podcast, listened to the whole thing, checked facebook compulsively every 10 minutes or so, sent/received about 20 text messages, synced about 1500 emails).
Obviously I won't know what the full improvement will be til I run out the battery, but initial impression is the reset all settings has helped improve battery life. It only took about 5 minutes to reset all of my settings (wallpaper, alerts, privacy, permissions, etc...) to what they were before the reset, so I wasn't too concerned about that minor inconvenience.