Well, in my opinion the battery life with iOS 6 on iPhone 4S is now much better!
1 % left and I have 8 hrs and 17 minutes usage and 1 day 7 hrs standby time. (I browsed the web, sent some E-Mails with pictures & received some text E-Mails, made some calls, used iMessage, Siri, Facebook, iCal, Contacts and other apps like Dropbox. Also I have 2 E-Mail accounts on "Push" and iCloud activated with all its features, except iCloud Mail and iTunes Match!)
With iOS 5.1.1 I hardly reached 6 hrs usage time.