Agree to disagree is going to have to cut it here. Even if the plot line was weak, the acting was superb, and no one could dissuade me. I thought it was an enjoyable movie, beautifully filmed and edited, and frankly it's nice to have Half Blood Prince as a comedic palate cleanser before war breaks out and everyone dies and no one is happy until the epilogue that no one liked anyways.
I wasn't a fan of the cinematography in CoS. Definitely didn't do Dumbledore's office much justice at all. That was one comment my girlfriend had about the film. Loooved the camera / audio work, because we actually got to see / feel / hear the atmosphere of Dumbledore's office. She said one good thing about films is that they can do things that books cannot do--and that was a prime example.
I liked Dumbledore a lot more too. Much more aloof. In GoF and OotP he just seemed... GRAWH ANGRY ALWAYS RROOOAAARR!!!!
Gambon seemed a bit more out of character, and not very aloof at all in this movie, especially in the ending. It's much more in Dumbledore's character to talk to Draco conversationally as opposed to how Yates made him.