Moving from a 4 to a 4s, I have noticed a significant decrease in battery life. While my experience is more anecdotal, than well-documented experimentation, here are my observations:
- I seem to drain North of 5%, for every 10 or so minutes of talking... actually, I'll bet I drain more like 7%, which is certainly more than I did on my 4
- I didn't worry much about battery life with my 4, but I've now totally drained my batt 2x, already today
- Last night, at midnight, I tole Siri to wake me up at 6am. The battery was at 43%, when I went to sleep. The alarm didn't go off, because the battery was dead...

I suspect my phone has something running on it that is negatively impacting battery life, but I pretty much have the same apps on it as I did on my 4. Otherwise, I love the 4s improvements. But I hope that a patch comes out soon... or, whatever app I have that's misbehaving, starts to behave better.
Oh, and my 4s is running noticeably hotter than my 4... what's up with that?