i've already said how i am not a fan. the movie couldn't really capture my attention- i tried watching it several times, on dvd and when on cable, and i either fell asleep or changed the channel every time.
i kinda fear it is something like the movie titanic--go after what broke box office records, for the sake of having a top moneymaker to build around.
except they already have some, in house or close to it, that are more time-tested.
I keep on saying a set of rides based on Narnia could have been awesome. I enjoyed the movies (i know the last wasn't Disney) but assuming they still have, or could re-acquire, rights, i would be much more excited about visiting Narnia as opposed to Avatar. my kids know narnia-they have no interest in Avatar.
Having just returned from WDW, i think it would take a lot for us to really spend more time in AK-and i personally like the park. We went on the safari-which was nicely changed from our last time in 2011-and the lion king show, and that was about it. Kali river had a crazy wait time and it was a day we just decided to bag early and spend some pool time. Avatarland would not change that. Narnia might. Or, if you wanted, why not do something with Wookies or Ewoks there--yea, i know SWLand is rumored for the studios, but if you are intent on mythical creatures...
i still think they should add a country (australia), and/or finally dust off some beastly kingdom ideas and run with it.
in terms of branching out to pull in non disney fans, Avatar doesn't resonate anywhere close to the two biggest family friendly, non-disney IP out there--Potter and Hobbit. not even close. so theres the challenge for imagineering...they absolutely have to make Avatarland such an amazing world with such cutting edge and awesome rides that the IP does not matter so much-even if you couldn't stand Avatar, you'd want to ride it.
but then, that gets back to, if you actually make the ride so awesome theming is largely irrelevant, then why bother with Avatar at all, why not do the beastly kingdom thing....don't use the IP/theming as a crutch