I think the movie was overall real good, and compared to other movies (like Goblet of Fire, where like half the book was skiped) I believe Half-Blood Prince did an awesome job. Yea, it did of course, miss a few points here and there but I believe that 98% of those points missed were necessary, such as transitions from one place to the other, or little stuff that happpened in the book to simply make it "realistic." The only three things I wish they had done just like in the book, is when leaving the cave, that Harry had been actually paralyzed during Dumbledore's assasination, and the fight in the end.