Speaking from a storyline perspective, 'Avatar" was another not-so-subtle jab at the evils of capitalism and colonialism, nostalgically praising a "more simple time." Not to say that that the story wasn't enjoyable despite that fact, as the acting and scene transitions were clearly well done, but it was predictable.
What accentuates the story of course, is the amazing special effects. Never has a director ever made it so believable that you, the audience, are in another world.