Everything has been done before. You have to remember this is a $10-$30 investment that is primarily intended to entertain you for a couple of hours. Does it make you laugh, does it make you think? sure. Does it cure cancer? no, but its not intended to. You can boil everything down to nothing, pretty much.
I also disagree about Sigourney weaver's performance. It was a very challenging role for any actor to work entirely in blue/green screen, and she carried a pretty well developed character in relatively few lines without upstaging everyone else who were "lower on the totem pole" stars.
Of course, you are well within your rights to criticize and I'm glad you did, it can be difficult to take a contrary position against the popular will. I don't want to sound defensive or whatever because I have no stake in helping James Cameron sell his movie. I simply disagree with your assessment.
Yeah, Sigourney's performance was good. It is also hard to judge because her most challenging scenes were as an avatar. Her performance was filtered through motion capture and 3D rendering. We don't have much experience judging such performances.
Right, as in much of Arthur C. Clarke's work, gods are technologically more advanced species and therefore not supernatural. Although the Na'vi seem to treat the neural net as a god and perform "spiritual" rituals for it. It isn't a god to us but is to the Na'vi.
I think our concept of God is confusing the concept of the Na'vi's spiritual network. Forget God, they had something that the human scientists could actually measure. It wouldn't be surprising that the cognitively advanced creatures around it would pay ommage to it and play out rituals to please it.