So here are my impressions. I can't remember the book all that well, so I don't really know how closely they followed the plot, but it seemed like they followed it pretty much the same as the previous movies.
Harry was as bitchy and annoying on screen as he was in the book. This was my least favorite of the books and so it made sense to me that I didn't like the movie as much as the previous ones. It didn't have nearly enough Snape (God I love Snape), Ron keeps getting better looking, The twins looked cuter in the Goblet of Fire with their seventies look, they had unfortunate haircuts in this one, and Harry is sort of short. I wonder if he'll have a growth spurt? Dolores Umbridge was PERFECT. She was an unholy terror.
You have to sit through the first half of bitchy harry before the second half picks up and the action starts. Sirius' death felt a bit rushed, and darn it, there wasn't nearly enough Snape! Or for that matter Bellatrix Lestrange. Helena Bonham Carter was fantastic, but they needed more of her. And I never realized before, probably because I hadn't seen it yet, but Hagrid is Robbie Coltrane of Cracker fame. My friend recommended this British crime series to me about a psychologist that is brilliant, but a deeply flawed man. He has a gambling problem, drinks and smokes too much, and uses highly questionable methods. I love it. I always liked Hagrid, but now I might love him.
I really liked Book 6, so I'm sure I'll enjoy that movie more. And not to mention Book 7, only a week away from being released!