What GendoIkari said, to a good extent. It also wasn't very funny, whereas a Pixar movie like Cars may not be thoughtprovoking or inspiring or emotional it's at least good for a few laughs. Brave's humor was largely physical comedy iirc, and not good quality stuff either.
A lot of Brave was like, National Geographic channel kind of stuff, where certain scenes or action sequences were taking place because the scottish scenery or the newest way of rendering animals was being tried out, in a couple places it seemed to be more of a tech demo than a movie in this way, because the attention was drawn away from the characters. I'd say the characters and plot, but I wanted to be drawn away from the plot because it was a dull, cliche plot.
It didn't help that the trailers promoting the movie were borderline dishonest. Which I guess shouldn't count against the movie itself, but if you saw the movie you probably saw the trailer first and the expectation versus reality rift doesn't improve the experience.