I used iOS 5 (on iPad 2 and iP4) since first beta and had no issues in that matter.
You guys need to remember that probably quite a few folks play with Siri now and Siri needs data to work.
Other than that hard to tell but my guts tell me battery is same as it was on iP4 while 4s needs more power to function. If I'm right then apple is literally milking the fanboy cow to the limit.