First of all, we all know this movie sucked, but there's one fact: It was originally planned to be named like the animated series is based: Avatar. But unfortunately, James Cameron released a non-related but awesome movie called... Avatar. So, instead they put the subtitle of the series as the official name of the movie.
And then we got many issues like the lack of asian actors, to the aforementioned acting and story. It gained various Razzies.