I'm having the same issue. With 5.1, my battery drain was decent. I could go a full work day with decent usage (text, web browsing, app usage, etc.) and end the day with 50-60% battery. After updating to 5.1.1, I can almost watch the battery drain, with no apps running or using the phone.
I had a voice call that lasted about ten minutes and my battery dropped almost 10%. I'm going to do a restore and go back to 5.1. I can't make it through a workday like this. My phone has been off the charger for approximately an hour (100% charge). I've barely used it and it's currently at 93%. Btw, I have an iPhone 4. If apple hasn't fixed this issue by the time my upgrade comes around, I'm going Android.