I'm going to begin by praising the film's courage to do something completely different. In almost every Western film ever, the person who defies tradition is always seen as the hero. So, when Pixar decided that defying tradition was a villainous act, that was a good way for me to learn something new from this film.
Where I think the film suffers is as follows: it subverted the black-and-white thinking of previous films, such as the Little Mermaid as one reviewer below commented...but ironically, it just ends up being black-and-white thinking the other way
In my opinion, that doesn't work. Both Elinor and Merida were behaving very badly. They both have to learn to make some compromises. The problem, however, is that since the film focuses on Merida's actions, most of the character development is on Merida's part and on Merida's flaws. The only change Elinor has to make is that she ends up allowing Merida to choose her own husband.
I'm not diminishing Elinor's part in solving the conflicts of the film; my problem is with the "pacing". We get oodles and oodles of scenes of Merida learning she was wrong, but Elinor admits she was wrong only once. It's admittedly quite an admission, but it's still a lopsided picture the film is presenting us with.
I'm really referring to a mathematical balance, not an "argument balance." The audience walks away with the impression of Merida as a brat, because instead of portraying tradition as an ambiguous affair as opposed to the tradition-defying heroes of the past, Pixar presents us with a very black-and-white picture, but the other way around! The lesson audiences walk away with, if not the lesson Pixar intended, is clear-cut: If you defy tradition for any reason, you're childish and you need to have your will and your spirit crushed.
It's sort of like if I decided Superman wasn't perfect, but I worship Lex Luthor instead. That only provides an illusion of complexity; my point of view is still narrow, I've merely exchanged one set of blinders for another one.
I'm not criticizing the main premise of this movie. It needed to be done, and it was a courageous step to take. I merely have a problem with the way it was executed.