I have seen the entire AVATAR: The Last Airbender cartoon series by Nickelodeon via Netflix streaming. I liked it so much that I ended up ordering the box sets of the 3 seasons as well which now proudly sit on my DVD shelving.
A friend suggested that it would be better to watch the live-action The Last Airbender first, before the cartoon, and there is probably some merit in this but I did not do so.
But I did get around to watching it, and in the main, I can say, it's not that bad. It's not good by any stretch of the imagination, but it's not terrible either. Its main faults lie in a poorly written script and bad acting from inexperienced child actors. The film does not tell the entire story and concludes with the season finale at the North Pole, with its climatic battle and resolution.
The following critique really nails a lot of what is wrong with the movie, and does so in a way that makes me laugh every time:
I think I would've been more appreciative of the film if they would've taken themselves less seriously and been a bit more Zany. I can accept the Fire Nation being changed to being more South Asian, resembling Indians and Pakistanis--but if they were going to go that route, I'd almost rather they went "Full Bollywood" with it, cheese it up with more camp, especially given the lackluster performances elsewhere. Either that or cast Sokka with a genuine comedic actor like Clark Duke, say, and give him a script that exploits his comedic genius; What's interesting is how much more emotionally compelling the voice actors' performances were over the live action cast...the best part of the movie DVD are the special features where the creators of the Animation are interviewed and talk about their own original inspirations for the show...that is informative and quite worth watching.