Well, of course the Potter movies are a Hollywood franchise, so their stories are always cobbled around a set of requisite elements, lots of broom-flying and people getting knocked over by magic and whatnot. Staircases will move, pictures will move, Alan Rickman will camp it up. Someone will grab Daniel Radcliffe by the shoulders and gaze into his eyes while he goggles back at them. These things are known.
But I have to admit I don't really watch them as films, more as fannish spectacle. I go to giggle over the little things that delight me, and shake my head over the little things that WTF me. I giggled when Dudley first appeared in all his upper-middle-class ghetto fabulousness. I giggled when Dumbledore announced himself at Harry's trial: "Albus Percival Wulfric...Brian...Dumbledore." Stuff like that.
I giggled a lot at Umbridge - her too-wide smile, her breathless little voice, her Thatcherite hair, her expanding wall of proclamations. I enjoyed her, my friends, and her kitten cardie too. Luna was good so far as she went, though I missed the Quibbler.
Ron always has the most thankless role in the movies (i.e., forgetting that his best friend's parents were tragically murdered, so the audience can be reminded of this important plot point; saying "I'll go easy on you" to Hermione before getting his ass whupped, to provide the obligatory grrlpower moment), so I was glad that in this one he was allowed a few moments of dignity, as well.
Not to leave out the CG people, I say, Kreacher thumbs up, Grawp thumbs down. He had all the texture of Jello pudding.