I use my 8800 HEAVILY... GPS to and from work (yes, i know how to get to work lol) but i use it just to use it, and the drive is 30min each way... i do use the "on at turns" function but hit the space bar quite often to see the map just for kicks. I use about 5 minutes of internet a few times a day, and I've watched atleast 30 minutes of videos, maybe around 5 emails + few text messages, get on ramble for about 15 minutes, use pocket express a few times for sports scores, listen to a couple songs here and there, stay connected to bluetooth all day, and my battery is at 55% right now.
I CANNOT COMPLAIN. And i will say that the battery life has only gotten better, not worse.
I truly believe you have a faulty battery if your losing that much power so quickly.