Nail head hit.
Why is District 9 getting such rave reviews? It's told in an interesting and new way, has great character development and keeps you on the edge of your seat ... and is not self-righteous in any way.
Avatar, while technologically astounding, looks to be the same-old, same-old big budget blockbuster, told in the same way that everything else is told. Of course, we don't KNOW that yet, but the teaser trailer certainly sells it like that.
I personally have faith in Cameron as a story-teller, and believe he will find some way to make Avatar stand out (other than through technology). But will general audiences give it that chance, after seeing this teaser? That is the question.
I do think District 9 is a game-changer. It woke audiences up out of a stupor... just imagine if Transformers was told in a similar fashion, instead of typical blockbuster fare? Keep all the insane explosions and awesome alien robot fights, but tell it from a different perspective and it would be even better!