My iP4S holds charge like a sieve holds water. I've gone thru and turned off everything to try and save battery power but it just dies super quick. Did the reboot, reloaded the software but I've had to charge it three times today and normally it needs to hit the charger 2/3 of the way thru the day.
Actually never have been impressed with the batt life of this compared to my BB 9650 but since 90% of the rest of the phone was amazing, I looked past it...getting depressed
2 things i may suggest:
1) try resetting all settings [Settings > General > Reset > Reset All Settings]
*you will need to reconfigure most of your settings but may be worth it (check your email settings too)
Or...
2) restore device and Setup as New iPhone (No Backup)
i suggest doing this and using your device for a little bit before loading a backup back onto the device so you can rule out some sort of wonky backup. you may want to just set it up fresh anyways
FYI: i Setup as New when the GM was released and had 0 issues with battery performance (iPhone 4S)