Iphone 4S / iOS 5 Battery Drain

Hi Guys,

I am having massive problems using the iphone 4s, it doesn't last a day. I have followed all steps on the forum but it doesn't change the drain rate. My boss has a iPhone 4 on iOS 5 and when we sat down to the desk, he had 100%, I had 74%. Both took off the charger at the same time as well as same usage and settings.

Is my phone faulty? Should I take it back? I can't carry on using it if it won't last a day!

Cheers, Sam