The first couple of days my N4's battery life seemed rather poor. By "poor" I mean like my iPhone 4S's battery life, which is horrible.
After going through a few charge cycles, though, it seems to have gotten better. I attribute that to the battery breaking in as well as me better getting to know the system and tuning it for better battery life. At first I left live wallpaper on, threw on a bunch of widgets, etc. Now the only widget I have aside from the clock (hmmm? maybe that should go too) is the power control widget (which I love!).
I have been turning off the GPS a lot too.
I also am leaving brightness at auto. It seems to work better on auto than my iPhone does. Better yet, the power control widget lets me set it instantly to 0%, 50%, and--for those demo times
--100%. (And then one more tap back to auto.)
Michael