My son and I are fans of the book series, and had really high hopes for this movie. We would have had no problem with the details of the book being changed; in fact, we expected that. However, this very disjointed, strange movie was just very poorly written. It was as if the director and writer just made no effort to establish anything, and the characters just jumped around from scene to scene for no obvious reason. Very, very disappointing.
"Half-blood Prince" is easily the most humorous of the six Harry Potter movies. It is hampered slightly by an ending that seemed anticlimactic, but is still exceptionally enjoyable.