I loved this book when it came out and I was going to read it again before going to see the movie but I'm glad I didn't. Probably for the first time I got to watch a HP movie knowing the essence of the story without nit-piking every detail. Yes they changed things, they had to, but I think overall the movie is probably the best of the series so far.
It was funnier than I was expecting, and actually had a lot more smooching and "relationship stuff" than I remember from the book. The girl who played Lavender Brown was fantastic as was Rupert Grint (but when isn't he fantastic). Oh and when Ron died (even though I knew he was coming back) it was horrendous to watch, really horrendous!
Both Daniel Radcliffe and Emma Watson's acting has improved immensely. Radcliffe's especially and I have to say I was quite happy to watch him carry this movie from beginning to end, something which I've always cringed at before.
But the star of the show for me was Tom Felton as Draco Malfoy. He was fantastic! The sense of fear, desperation and hopelessness of his situation was portrayed brilliantly throughout the movie and I got the Sectum Sempra (sp?) scene I wanted. I always thought HBP was as much Draco's story as Harry's and the movie really paid dues to that.
Other than that all the adult actors did a fantastic job as usual. (Rickman in particular is looking younger than I've ever see him as Snape).
The one thing I did notice was all the little first years running around. So cute! I really wanted them to get in Ron's nicknames for the first years because, honestly, they did look tinchy.
P.S. Harry on drugs Felix Felicitous is hilarious!