I've had my phone since November of last year (7 months), and in my experience, it seems as though the single biggest battery killer for this phone is data. I use my phone primarily for music, with a little bit of browsing, texting, online-based games, and facebook here and there. And my home screens are filled with widgets. Now, for the first 6 months, i never seemed to ever get more than 4-5 hours off a single charge. Even if i did NOTHING with it, the battery would still drain. One time i left it unplugged overnight at 100%, and woke up to a 66% battery.
It actually wasn't until a couple weeks ago that i finally tried something that had never occurred to me before... i turned my data off (only because i was in a bad coverage area anyway) and left it unplugged overnight as an experiment. I woke up and was SHOCKED to see it still at 100%! The battery consumption is DRAMATICALLY improved without the data on. Its like night and day. So now i keep my data off when i'm not using it (similar to how you would turn the light off when you leave a room to save energy) and i am routinely getting as much as 10 hours of battery life despite heavy music usage (haven't tried a completely data free day yet though. It might last even longer than that). I can literally play music continuously for the better part of an entire day now. About the same lifespan as my mp3 player, which has officially been replaced.