The movie is about an Avatar, who has returned after 100 years to bring balance to the world. There are four nations: Water, Fire, Air, and Earth. Fire Nation has taken over the world in the last 100 years. It is the Avatar's job to master all four elements and bring balance.
I have seen the original animated series. The characters in the TV shows are so lively. The storyline can easily be followed. The main character, Aang, is the best in the series. He is about 10 year old, and he acts like it. He does not understand few things and Katara and Sokka, his friends from Southern Water Tribe, act like his body guards, protecting him and guiding him.
The movie failed to capture all these elements. The characters were flat. Aang, played by Noah Ringer, was not animated. According to Wikipedia, Noah is Black Belt, but in the movie, even his martial arts did not seem to be at his best. I do not know much about martial arts. I wanted to see some "jaw-dropping" moves. Katara, played by Nicola Peltz, was the best character. I felt she did justice to the role. Jackson Rathbone as Sukko was also good, but he was more mature in the movie than the series. His childishness is what makes the series fun and same goes for Aang.
As for the story line, it was confusing. I have seen most of the series and the movie was still hard to follow. Imagine going to the movie without having any background knowledge about the storyline. I think that M. Night Shyamalan should have just concentrated on this movie instead of worrying about the trilogy. The movie had so much potential, but it got lost somewhere in the transition.
I give this movie 5 out of 10. Even though this movie was not what I expected, I will still watch the remaining two in the trilogy.