Good movie. DON'T bring your 8-year old, or at least, I'm not bringing mine. Two scenes are two horrible or scary and most of the rest is psychological development or despairing.
Book is intense and dark, and I thought the movie pretty faithfully covered the main bits. I agree with the people who have said that Hedwig, esp. wasn't nearly as important a loss to Harry in the movie, but the sense of loss had already been established in other ways. I also agree the dancing scene wasn't well done.
Leaves you in a pretty dark place at the very end. Definitely plan on chocolate afterwards