I thought it was rather good myself, although I will allow that it used a perfectly standard plot. But I thought it executed the plot quite well, and seriously, archetypical plots make up some of my favorite stories. And it was gorgeous, even on a normal screen.
Interestingly, I nosed around and found quite a bit of cannon backstory at the avatar wiki (or they called it something like that...it wasn't really a wiki though, being small and linear) Anyway, there was a fair amound of backstory gems that actually made the movie make more sense...
A) Apparently, the Navi don't use actual DNA, some sort of translation process was required to translate human genes into native ones, and splice them in. The DNA mention in the movie was just nontechnical shorthand
B) Unobtanium (I think the name is great lampshade hanging) is some sort of superconducting/antigrav material. It's used on earth for transportation purposes, also plays a big role in spaceship travel (cough....oil/melange spice). Still, it's use (making things float) ties in well with it sitting under the tallest trees (weight reduction) and making up the floating mountains....which I thought were ridiculous but stunning enough for me not to care.
C) The corporation in charge of mining was prohibited by treaty from bringing WMD's into space, and was under pressure from the governments of earth to avoid outright genocidal disasters. Though they were also able to bribe enough to do some smaller scale exploitation. And, has been stated before, really mechs and gunships and whatnot are pretty heavy duty against bows and arrows (and defeated them repeatedly). And the exec on the ground was clearly too weak willed to push for an all out "nuke from orbit" strategy, and had to be coaxed into a military option for just knocking down one tree. The corporation can no more get away with an outright nuclear or biotech slaughter of the Navi than Exxon can get away with carpet bombing a section of the rainforest before putting up oil wells.