I'm having some trouble with my new Nook too. The battery goes down very quickly, going from 100% to 70% or so in a few hours. I did side load several books (120 or so) and read for a few hours.
I was just wondering if like the Kindle Wifi if it processes the books, which in turn drains the battery quicker. I have put more than 1200 books on it win in the two weeks I've had it so that would be a large battery drain if it's anything like the Kindle.
As it is I'm getting only a few days on a charge. Returning it would be hard (if not impossible) as I live in Canada and someone I know who was going the Vegas pick it up for me.