Warning: Lots of spoilers below, and even if you've read the book but not have seen the movie, there's a lot that was changed around and/or left out in the movie, so at least watch the movie first if you don't want to know what happens.
I think David Yates did a good job, especially setting the tone of the movie. There were a few laughs, but overall the book was quite dark, and the movie reflected that. Because the book is sooooo long and full of detail, the script writers had to make adjustments and either gloss over certain plot points, change them around or eliminate them completely. All in all, the script itself was mostly plausible, but things will never truly make sense unless you've read the book at least once.
However, I really wished they did a two-parter or made the movie a bit longer, as there was so much detail that I would have liked to seen. As much as David Yates tried to restrain the pace, there still was a feeling that there was so much going on that the movie felt a bit rushed.
Things I liked:
- Dorlorus Umbridge was really well casted. Imedla Staunton had her "hem hem"s down to T, and I felt like punching her from the beginning. I also loved her pink cat room.
- I think they did a pretty good job with Luna Lovegood. She's always described as talking with a dreamy-like, sing-song voice, and I always felt that Luna never was quite there mentally. That came through well for me.
- Bellatrix, also well casted. She's one nasty piece of work
- How they portray the Extensible Ears, much better than how I imagined it
- I'm glad the fight scene was short; it was well played out in the movie. That part was particularly tedious to read in the book and I always felt that JKR should have taken some details out of this section of the book.
- The Department of Mystery was how I imagined it to be. The Ministry of Magic set was better than how I had imagined it
- I liked how they made Cho the snitch, it does help show their relationship fizzle (I also was never a very big Cho fan, so didn't see what Harry ever saw in her besides a pretty face)
- We saw hints of Ginny's true magical power capabilities. I think we'll be seeing way more of that from her in Book 7.
- Dudley's costume, that was hilarious! Harry Melling looked like he was having way too much fun playing the role, even after he was kissed by a Dementor
- Even in the brief flashback, I thought Young Snape was hot! and not a greaseball at all
- I'm glad they decided to develop Neville's character more in the movie. I also think he will have a large part to play in Book 7
- I was really impressed with the special effects in the Ministry fight scene. Kudos to those people.
Things I didn't like:
- They took out Mrs. Black's shrieking portrait. That's one of the things I did want to see
- I'm hoping that they do something with Ginny dating life in Movie 6, she shouldn't have been shown still pining for Harry, but should be "over him" already. And her characterization in the book was much stronger, but that wasn't shown at all in the movie. I particularly wished that they kept the Dungbomb scene in.
- They did a poor job of not explaining why Harry was able to see thing through the eyes of the snake when it attacked Mr. Weasley
- Not showing that Petunia got that Howler from Dumbledore. There's more going on with her than meets the eye, I think, and will probably be reveled in book 7
- That they didn't show Harry not building up his anger at the beginning because he felt left out of the loop and was kept wondering why no one did anything about Voldermort (he didn't know what they were saying about him in the Daily Prophet until they he got to Grimmauld Place)
- They cut out Quiddich completely from the movie
- The scene where Hargid was explaining his trip to go see the giants was weak, not how it was scripted, but how it played out
- Snape was totally out of character when Umbridge was questioning his teach abilities. What happened with the snarl? I get what David Yates was trying to show, but I wished Snape stayed in character for that scene.
- I think that changing the scene in the movie where Voldermort does enter Harry's brain, the script is trying to gloss over the fact that Voldermort doesn't understand love, and hence covers in the book the whole speech that Dumbledore gave at the end to Harry
- I did catch one continuity error. Hermonie had no trouble saying Voldermort's name at the beginning of the movie, yet at Hog's Head, she had to force herself to say it. (She should have been saying You-know-who up to this point)
- No mention of how Kretcher went to Bellatrix and Narcissa to tell them abou the OoTP. Not a big sticking point IMO. How they ended up working around it was plausible.
- I'm a loser. I love London, and loved recognizing the city in the movie. I like Westminster Station's look (it's one of the nicer Tube stations that I've seen), and was wondering what scene they were filming there when I heard that they did film there. I actually passed through London a month before they filmed that scene.
Well, that's all I remember for now. I'm certain that more will come to me later. All in all, a good movie, and probably the best one so far.
Movie rating: 8 out of 10