I really did not like the movie. Like, at all. The movies plot was nothing what the book was about, and they changed so many things it was disturbing. First of all, it's called Harry Potter and the Half-Blood Prince. The movie went as far as to actually PUTTING the name in the book Harry found but other than

Spoiler:
Snape saying he was the half-blood prince


then nothing else had to do with it. They spent WAY to much with the new Professor and even took out the flashback when Harry saw Snape getting messed with by Harry's dad and the group. ALSO, they took out the ending scene
Spoiler:
When Dumbledore dies all the merpeople come out and centaurs etc


Which would have been really cool to see but no they changed that too. Even the fights were pretty lame I mean jeez :\ I think number 4 still reigns as the best entrance to the series...