Since I got my iPhone 4s I was very disappointed with the battery life: it looks like I'm not the only one..
During the last days I found several solutions that really improved my battery life
You have to read for days to find the good tips among hundred discussions, this is why I'm sharing those here
I'm still hoping that Apple will do something soon to improve IOS5 battery eating disorder
1) Fully charge the battery with the iPhone off
At night -or when you do not need it- plug in your iPhone to the charger , then switch it off
pulling the red tab on the screen and let it charge.
Do not switch it off before and plug in after because
the iPhone will start back automatically
The battery will go to 100% and it will last longer
This is a procedure I have done in the past even with old iPhone and iPad and I always found that works great.
Same for laptop.
2) Turn off Setting Time Zone function
in Locations (system services). It never turns off location searching so it drains the battery.
This setting was draining my battery 3% in one hour with everything off.
3) Turn off Diagnostic & Usage Data.
Settings > General > About > Diagnostic & Usage > Diagnostic & Usage Data.
Another big improvement
4) Brightness at the minimum you can stand
5) iCloud off
I use it to sync when I'm at home and with wi-fi for now: hopefully Apple will come up with some fixes
I had to kill several operations to get a decent battery life: I do not think this is what you need to do when you buy an expensive phone
Everything should work fine and the battery last as long as promised...
6) No iCloud cellular use
Settings > iCloud > Documents & Data > Use Cellular = OFF
7) Turn off Time Zone and Ask to join networks
8) Do not leave iMessage in standby when you do not use it
Quit as soon as you finish sending messages
Thanks to everyone who suggested all these tricks : it's difficult to go back and find them all but
my gratitude goes to all of you !