The iPhone 4S should give users 8 hours of talk time and 6 hours of Internet over 3G. I have yet to meet anyone getting anything close to that. Why? There are a few bugs in iOS 5 that is killing the life out of your battery. Some of the bugs are the calendar bug and the time zone bug.
When the calendar app is turned on in the Notifications Center, events re-ordering themselves constantly. The only fix is to disable the calendar app within the Notifications center. The Time Zone bug constantly pings servers to update location and time zone settings. To turn this off go to is Settings, Location Services, System Service, Setting Time Zone and then turn off the location services.
Next go to Settings, Location Services and look through apps that are using the location services. Turn off the location services for anything that you dont use or really does not need it. I’m looking at you Soundhound. Then go to System Services disable Diagnostics & Usage, Compass Calibration,… You know what turn everything off except Call Network Serach.
Take a look at your accounts and turn off Push. Pick Fetch and select Hourly. Only turn on Wifi and Bluetooth when you need them. Turn off auto-brightness and slide screen brightness halfway down. We hope Apple rolls out an update to iOS 5 that will take of these issues soon. In the meantime look under notifications and location services for ways to cut the fat so to speak.