People are missing the point
SPOILERS abound
I keep seeing people talk about this movie like it's something it's not. Some reviewers are saying this is a cut and paste "rebellious girl acts like a boy" story. Others say the villain should have been cut out entirely. They are wrong.
I just watched this movie for the first time, and the most important scene can be missed if one blinks or is already writing off the end because they think they already know what is going to happen. Mor'du is killed, and his spirit is shown to be very grateful, at peace, even. His spirit looks much like the wisps seen throughout the movie. This reveals that he was the one to be the one causing wisps to appear everywhere and his goal was to be freed of his physical trapping. He was resident in the beast, could not control it, much like Merida's mother as a bear at a few points in the movie. So, Mor'du has been causing the wisps all along and influenced Merida to become who she was and be at odds with family (her mother) so that, like Mor'du, she would ultimately make a deal with the witch (which he led her to). Mor'du wished for death, and was somehow able to create those wisps in order to lead Merida to making some of the same decisions he did, so she could discover his past and cross paths with him.
Sure, Merida was already going to be rebellious, but from the first scene it was the wisps that lured her into being even more independent from her mother and this continues throughout the film. She was guided into this pattern of behavior, so, in my opinion, cannot fully be blamed for her actions. She kept saying it wasn't her fault and blamed the witch. She was mostly right; she somehow knew she wasn't to blame. Yet, there was much more to it than that.
I made this connection during that end scene when the beast of Mor'du is killed. This is just good storytelling. I give it 8/10