I'm on my 4S anywhere from 2-5hrs a day depending on how busy I am and if I have time to just chill. A lot of my time is also spent on my iPad as well, instead of viewing the forums or whatever on my 4S I'll grab my iPad.
Later in the evening when I'm ready to turn in for the night my iPad becomes my tv
Edit: oops my bad, I just realized this is in the iP4 forum
I am on my iPhone 5-6 hours a day throughout the day. Between calls, texts, Facebook, twitter, google+, email... It's just the one item that I have on me all the time.