This is my first iPhone (got it about 2 weeks ago), which I'm finding to be much more enjoyable to use than my Epic 4G, so I've been using it a lot more. I'd also note that I spend a lot of time studying at home or coffee shops, and we have WiFi at work, so I use WiFi whenever I can. In 2 weeks, I've used about 350 MB, but I've just started using Pandora when I'm on the road, so I imagine for that usage to go up. Also, I just realized that Netflix on my 4S is much more stable than it was on my Epic, so I'll definitely be using it for those long cardio sessions at the gym!