Character design did not match tone of the story
I think the character design was a severe misstep. It was far too "cartoony" and characters looked like a caricatures. I don't know why the Producers chose to go with this style rather than adapting the look of the original source material, which they have always tried to do with past movies.
Frankly the animation style reminded me of the Curious George movie. Not a gter int good thing considering that the story is so dark.