Talking about flavor, I think this is the first Potter movie to have any. It feels more open, with more possibilities, and for once it looked like the children could get hurt, physically and emotionally.
Other things I noticed: In the first two Potter movies, Hogwarts looked liked Cinderella's Castle in Disneyland (or world, pareho lang yan), and it was situated in what looked like a golf course or garden. Here, the school building has real character, rather ominous looking with the Dementors floating about, and the surrounding landscape is wilder, more unsettled (it was shot in Scotland, I hear).
Also, more ethnic students in view--Chinese, Indian. They were mostly background fodder in the previous movies.
I don't know how good an adaptation this is of the Potter books--haven't read them. I do acknowledge the plot is as confusing as ever, and that, as Potter points out, nothing is really resolved.
But I'm not looking at the movies as adaptations; I'm looking at them as movies. This one, for once, works.
Incidentally, not only do I think this is a better film than any of the hobbit movies, I think Cuaron's A Little Princess is better than this movie. But I do like this very much.