I found this movie charming and very entertaining. Even being fourteen, I still love animated movies. Though I have to admit, the characters looked a bit Tim Burton-esk. But I though it was more of a nod to him than trying to rip off his artistic style.
Well, anyways, I thought the humor was clever and the art, though not Pixar, bright enough to capture a child's attention. I thought the part where he was explaining what happened when 'Igors' thought, and he turned around and opens a bottle with a old Igor's head very amusing. But I have to say, this movie requires a bit of a dark sense of humor, which I happen to have.
The only thing I found annoying was Eva's tiny arm. It was rather distracting. But if you're looking for a deep meaning, than I suppose it says to be yourself, and to let others be themselves and like them because of that. The only thing that was a bit offensive was the Blind Orphans bit at the end, but it would really fly over a kids head.
The violence was so mild, that I'm surprised people were even really commenting on it. I think five and up is fine.