Huge amount of slapstick felt at odds with the story.
I've seen nearly every Pixar movie (and I'm a pretty big fan of their approach to comedy), but was just absolutely blindsided by the really silly, almost Looney Tunes nature of the humor in this one.
Not necessarily because it was wackier than what they've done in the past, but because Pixar usually is so good at respecting the tone of their movies. A story like this (Pixar's first historical fantasy film) deserved to be grounded in a semblance of reality, but all the constant pratfalls, running around screaming, people getting comically hit with things (in ways that realistically, would kill or gravely injure them), and one-dimensional side characters just felt completely at odds with the story that was being told.
I liked some that stuff, sure. There's some genuine laughs to be had with Brave. But there was just such a massive quantity of this wacky "quick let's entertain the kids" violence-humor that grew repetitive and tiring very fast, and ultimately hurt the movie.
I can't say that this one was quite up to Pixar's par, and its humor is one of the chief things that felt bungled.