Very cute! I can definetly tell you put a lot more effort into the coloring than usual--I'm very impressed by the dark shadows on the faces and necks, followed by the semi-dark shadows. It's really amazing how we use a lot of the same coloring techniques, ne? I'm very impressed with the hair, too. You are just an EXPERT at cel-style shading, you know that?
I agree that some of the faces look slightly off--not so much Sasuke (I just think the black on his nose is a little thick) or Sakura, but I think the problem with Naruto is that his eyes aren't quite balanced. One seems to be a little bit higher than the other, which seems odd because he seems to be looking at us straight-on. Other than that, I don't notice anything askew.
I really am impressed with the textures on thier headbands--it looks just like mottled steel. :) And that is an EXCELLENT idea for the background--I'm really impressed with it. Great job!
Nice group picture and they look good against the BG. I'd agree though, that naruto looks kind of goofy. He kind of looks like Archie or something in that group there. Anyhow you have such nice clean colours with great use of whites. The only criticism I might levy is that maybe add more texture to the clothes. Overall great work though. Hey, why don't you try some Shaman King stuff. Your style would work well with that. Good luck with your future art!