I'm going to give my general feelings on the movie before delving into spoiler territory.
First let me start by saying that the movie is definitely VERY GOOD. You should go see it. ESPECIALLY go see it if you are a mother or a mother's daughter. While I enjoyed the movie wholeheartedly, every woman I know had a much more thorough experience than I as they connected with the mother/daughter relationship in the film very strongly, and I can understand why. It's definitely the movie's greatest asset and is rightly the centerpiece of the film. Even if you are a dude, you should still go see this movie because it's a damn good movie and it may still move you to tears even if you can't relate to Merida and her mother in quite the same way (though perhaps you'll feel something similar while watching the short "La Luna" before the movie).
Second, let me just say that you ought to stay until after the credits for a little bonus scene. No, Nick Fury doesn't show up to invite Merida to be the new Hawkeye... though maybe he should. Still, it's a good little payoff that's worth waiting for and for the love of god, these people worked hard to bring you entertainment and all they ask in return is that you memorize their names! Yes I stole that from the Simpsons. Sue me.
OK, now for the review proper. Some spoilers will happen beyond this point.