This is a fairly generic story wrapped in great visual effects and 3D imagery. But Avatar will probably become THE movie that will lead the way for other 3D productions. Unlike some previous 3D pieces I have seen, where the 3D effects become blatant and annoying, this one simply adds enough 3D effect to enhance the visual experience.
The story is a very typical and predictable "boy meets girl with a culture (species) clash/war good vs. evil plot that puts their love in jeopardy." If you think you've seen this story a dozen times in "conventional" movies; -- you have.
But, in spite of the predictability and tread-bare premise, Avatar is still a lot of fun to watch. If you can see it in an iMax theater, do it.