Apparently it won't open until 2018, three years after Avatar 3 is released. Avatar doesn't seem like the kind of franchise you make a theme park out of, given that James Cameron is not George Lucas.
Certainly unexpected, but will no doubt be interesting. Say what you will about the story and the characters, the environment would be pretty cool to explore, especially at night.
Plus it's a Disney Park. The other parks are fun, but Disney always goes the extra mile when it comes to service and the whole experience. We went to Disney, Universal, and Seaworld last year during Celebration (and will go again next year). Universal is pretty fun (especially the Harry Potter land) but Disney has a real magic to it; just like when I was 6.
I'm wondering when Star Wars land is going to be announced. You know it's gonna happen. There's just too much money in that brand for Disney and Lucas to pass up.