I love the Harry Potter series. They are fabulous. There is so much depth in the book and I understand that the movie can- in no way- have all the details that J.K. Rowling put into the books. But at least stick with the main storyline.
Harry Potter and the Half-Blood Prince was not what the movie was about. It was about Harry Potter and Ron and Hermonie's Relationship. At least that's how I felt. There was such a strong relationship that Harry gained with the Half-Blood Prince that was never discussed. There was also a extremely important relationship between the Half-Blood Prince, which was Snape if you missed the whisper in the movie that declared that, and Lilly that was NEVER talked about. Grimauld Place is now Harry's, which the movie never mentioned. Voldemort's past was touched a bit, but not about his parents or Grandparents. They never talked about WHY the Horcruxes where those Horcruxes... I have NO idea what the next movies are going to be about because all the crucial information in this one was left out.
Maybe if you've never read the book, or it's been a long time since you've read it, you may like it. But there could have been so much more potential. I really feel like this was the only movie that left out really really vital information. It was also the first Harry Potter movie that I left feeling like they missed the entire point of the book.
This article may sound a little harsh but it's really how I feel
http://www.moviesonline.ca/movie_review_detail.php?id=13440