You know, there are actually very few things about the Harry Potter movie adaptations that really bother me, which is saying something because normally book --> movie adaptations bug the living crap out of me. There were a lot of little things (like the fact that they gave Hermione all of Ron's lines so she could explain everything, when really that made no sense because as much as she'd read about wizarding culture, she hadn't grown up in it). Obviously the first two were... interesting. Sweet with some shades of darkness. But once they hit Prisoner of Azkaban and established an aesthetic that was a little darker and grittier, I bought whatever they wanted to feed me. The truth of the matter is... you really can't adapt a movie straight from the book or vice versa and expect it to translate it well. They're two completely different ways of storytelling. In a movie, you can set the tone, the lighting, underscore the emotion in two seconds, but it takes considerable more work to convey all of that in writing and 1) not have it be purple prose and 2) not have it be extraneous and 3) not make it seem like you're trying to hard.
I'm trying very hard to be loyal to the books here, but this deleted scene from Harry Potter & The Half Blood Prince totally blew me away. Beautiful! That four second shot of Snape tells you everything you need to know.
Hmmm... don't mind me, just thinkin' aloud...