Like you I'm getting around 3 hours, actually a little more using the default settings. I've set up a couple of different profiles based on how I use my tablet to experiment with. For example, note taking in a dark theatre on battery power, I really reduce the screen brightness, reduce the processor load, turn off the wifi, etc.... Another example, I have a full power profile on battery with the screen at full, processer cranking, etc.... On that full power battery profile I'm getting right at 2 hours. On the previously mentioned one, I'm getting a reading that tells me 3:45 or so, although I haven't really put this through paces yet.
All in all, the battery life expectations seem good to better than good for me.