It's very good to see an American animation studio making a film with a mature, complex storyline. However, it seems like they can't let go of more family-friendly style elements, such as cartoonish character designs. Not that I have a problem with that - I loved The Incredibles - but it clashes with the subject matter. On the other hand, I realize that it's very hard to make realistic 3D character models that don't look downright creepy (see The Polar Express).
I'm afraid that this movie is going to do poorly businesswise, though. The Animation Age Ghetto is still in full effect. Don Bluth's Titan: A. E. failed miserably back in the '90s, and Ralph Bakshi's output is likewise regarded dismally. (This may because Bakshi's work is mostly crap, but I digress.) Sadly, American animation is a long, long way from reaching the widespread acclaim the medium sees in Japan.
Still, as I said, it's good to see someone trying. I wish the filmmakers the best.