Well firstly, last I heard it only ranks well in the "highest grossing" when you don't adjust for inflation, and if you don't adjust for inflation it really means nothing.
no cool music
I thought the music was great. Especially when the World Tree was falling down and the Na'vi were perishing in the inferno. It's not the best, but good enough for me to download the OST.
Oh, and more holes in the stoyline.
What plot holes? I didn't pick up any glaring plot holes.
Main plot hole I found
-How on Earth can it not cost more to send a whole bunch of people and equipment into space for 3 years, pay them a wage that makes it worth going into space for 3 years, pay for these highly expensive avatars and wage a major war than the actual price they'll get for the ununium?
-They never really explained why the chief decided that Jake was alright. The only reason he had for changing his mind was that he said he was a "warrior". People have been trying for 3 years to get these people's trust, and all you had to do was say you are a warrior? Also, what benefit does it bring these people to take this guy on and teach him the ropes?
-Why the fuck do these people have tails? They don't seem to have any real use and they only seem to get in the way
-Why does nobody punch the main guy in the face? Also, how could any female possibly like him? Or male actually....