Avatar looks like fun. For starters, it's only a little over 2½ hours, which is usually good blockbuster length. Generally the longer they get, the more intolerable they become.
(Although The Dark Knight for example was way too long at that length. But it was just so bad it felt long I guess
)
And hey, it's got Sigourney Weaver on a space ship, there's a good chance it's great
Although I'm thinking they've also used the CGI to make her look younger, or the make-up department have really outdone themselves.