This is one of the darkest and more heartbreaking of the installments. Though the movie was very good, and I did enjoy it, I was also somewhat disappointed. Several important things to the final story were replaced with romance. Though I understand it's place in the movie, I still wish they would have given more to the idea of the Half Blood Prince. But the acting was phenomenal -- each actor provided their best performances yet. Daniel Radcliffe showed just how much he has grown as an actor, providing the amazing range Harry needed to go through during the movie.
Though I wish some more of the story could have been in it, I understand you can only fit in SO much. So, all in all, I really loved it, and highly suggest you go see it, especially if you are a fan. =]