Well, to reply to an earlier comment, Night has seen the series, and according to interviews he and his family are big fans of Avatar. Considering he basically volunteered to direct, I'm pretty sure he has seen the show.
I agree with what a lot of people are saying: the casting sucks.
First of all, race is a major part of the Avatar world. The water tribe members are meant to look like real live eskimos (skin color, facial features, etc) and I would venture to say that racially, Zuko and the people of the Fire nation are meant to look like Japanese people (pale skin, Asian features). However they screwed it up! they cast white people for the roles of Katara and Sokka, and a tan dude for Zuko!
Oh and Aang was supposed to be asian...come on man...he's a monk!...and there was a video on youtube for a kid who would have been PERFECT as Aang. Not only was he the right race and age, but he was also a friggin' beast at martial arts. Here's the link:
YouTube - Aang Audition (Sides&Martial Arts only)
Anyways, I hate Patel for Zuko (I mean why didn't they just use Zuko's voice actor, Dante Basco? he LOOKS like Zuko! and with a bit of training he'd have the martial arts down)
Dante Basco:
But at least Patel has the martial Arts background and good acting skills...