It lacked the wide age range appeal other Pixar movies manage to pull off. I didn't like the fundamental elements as a metaphor for race/culture either, it's sort of racist to imply people of different backgrounds are so fundamentally different like that, although it did serve as a strong visual for the story. It would have been more accurate if the characters were projecting fundamental differences on to the same element, like different phases of water or something. That was the only real thing I thought was actually wrong with it, otherwise it just lacked the magic that other Pixar movies have.