A couple of problems with this as a kids movie

This wasn't a bad movie, but it fits a narrow niche of appropriateness for children:

The titular character's bad behavior is seen as cool with positive reinforcement. Her breaking things, acting rowdy and violent while blasting "metal" music could easily end up with your child acting up afterwards because it's fun and funny.

As common with way too many children's movies (looking at you Disney), there's a complete disregard to democracy and too much focus on entitled destiny. It's a minor point, but after every.single.kids.movie, a parent shouldn't have to explain to their child that they aren't a princess, they shouldn't count on a prince to elevate their status or pledge loyalty to a dictator/monarch, but with hard work and determination they achieve great things in life.