[NOTE: I haven't seen Avatar, though being a fan of Aliens and some of James Cameron's other work (the less about True Lies the better), I am inclined to do so.  Still, spoiler warning if you haven't seen either Avatar or District 9.]

Annalee Newitz of Io9 hits the analysis on the head when she critiques Avatar as just the latest scifi rehash of an old white guilt fantasy.  From the previews I have seen, her take looks spot on.

She goes on to talk about white privilege and makes a good connection with the situation of Wikus in District 9:

Think of it this way. Avatar is a fantasy about ceasing to be
white, giving up the old human meatsack to join the blue people, but
never losing white privilege. Jake never really knows what it's like to
be a Na'vi because he always has the option to switch back into human
mode. Interestingly, Wikus in District 9 learns a very
different lesson. He's becoming alien and he can't go back. He has no
other choice but to live in the slums and eat catfood. And guess what?
He really hates it. He helps his alien buddy to escape Earth solely
because he's hoping the guy will come back in a few years with a "cure"
for his alienness. When whites fantasize about becoming other races,
it's only fun if they can blithely ignore the fundamental experience of
being an oppressed racial group. Which is that you are oppressed, and
nobody will let you be a leader of anything.

She concludes with:

Whites need to stop remaking the white guilt story, which is a sneaky
way of turning every story about people of color into a story about
being white. Speaking as a white person, I don't need to hear more
about my own racial experience. I'd like to watch some movies about
people of color (ahem, aliens), from the perspective of that group,
without injecting a random white (erm, human) character to explain
everything to me. Science fiction is exciting because it promises to
show the world and the universe from perspectives radically unlike what
we've seen before. But until white people stop making movies like Avatar, I fear that I'm doomed to see the same old story again and again.

Praise Be!