Wow. I just watched the whole series (so far), and I have to say I was caught off-guard by how good this series is.
It's like these American writers took all the stuff about shows like Naruto and Bleach that is good and left out the bad, threw in a good dose of mythology from a whole bunch of cultures, added some fantasy ala 'The Neverending Story', took a bunch of cues from Hayao Miyazaki and made it into the best story they could possibly think of for a children's show, then proceded to hand it over to an anime studio with an American budget.
I wish they made shows like this when I was a kid. It's really good. Especially for it's demographic. I probably wouldn't be as impressed if it was for an older audience, but any children's show that can have an epic war and something as creepy as the 'face stealer' from the season finale in it has my vote.
It's very well-written, with mostly three-dimensional characters (One of the villains, Zuko, is pretty one-dimensional before the second season develops him more) and a compelling story. Plus; it has the edge on manga-adapted anime by having self-contained conflicts and storylines with a climax in almost every episode (yet the writers are good enough to not let these overshadow the main story).
Anyone else follow this?