The battery in my 4S is excellent. I get about 10 hours of actual usage through the day from a single charge overnight. Also, when it's in standby, it doesn't drop any percentage at all... I was in College yesterday and had 96% battery, checked it 4 hours later and it was still at 96%.
However, I do have the brightness pretty low, with wifi and Bluetooth also switched off.
The most power hungry things of all though, are the things that are using the GPS constantly, which are:
Location Services > System Services (all the way at the bottom) > Setting Time Zone.
If that had a Purple arrow next to it, then you've just found your power leech. Well done.
If there's something else purple tinted in there too, try turning that off as well.

For some horrible, nasty reason, Apple chose to hide all this information from you, unless you open up System Services and see for yourself. >.<
Since I also use Twitter, Facebook and Pages a lot, I turned off location services for them too, since they were regularly bringing up that dreaded arrow next to my battery (as if it were sucking those percentages right out). Why does Pages use Location Services anyway? LOL.
Hope this helps someone perhaps a little bit with their battery troubles.
