I don't have anything against it, per se -- I'll put it in my Netflix queue when it comes out on disc. But it doesn't look that interesting -- the holiday launch movie I really wanted to see was A Single Man (thoroughly brilliant), and I saw that. I also saw Up in the Air, which was not my choice (it was comme ci, comme ça).
Don't waste your time renting it. There's really no point to watching Avatar at home. There's a weak story, characters you don't care about, and a stupid bad guy. The absolute only reason to see it are the effects and those will look best in 3D IMAX.