Well it's a good thing that I haven't seen the cartoon series as I might actually be able to enjoy the movie a little bit.
I agree that the actress that plays Katara looks like she can't act worth shit. Article say she's 15. FIFTEEN? She looks and acts like a bratty 9 year old bitch who overemotes and overacts her parts, crying and wimpering and getting crotch-bleeding emotional when it's not required. In any case, isn't the lead female supposed to be tough and a fighter, not a whiny submissive bitch who expects the guy to save her every time?
Also, there are too many white people in this film. I would expect an Indian director to know better, considering he's a minority in the USA, and not pull the "Let's cast only white people" racist bullshit that Hollywood always pulls, but apparently even minorities can be racist, and he only casts whites and Indian people. Between the female lead being weak and the all-white cast (except for Indians, who are all villains), Shamalamadingdong comes off as acting like a racist WASP. Maybe he wasn't even in charge of casting, maybe it was some old white exec who did it.