I liked parts of it, but the pacing felt jarring in many places, lots of exposition sometimes (esp. at the beginning) that made the scenes feel weird but maybe that couldn't really be helped... I may see it again, but I think I need to see part 2 before I can really make up my mind about this one. Walking out of the theater, it really did feel like only part of a story.
Some weird editing and awkward directing, but loved the acting all around. Haven't liked Gambon previously for the most part, but no major complaints about him here. Loved seeing more comedic side of Harry come through, and thought Dan played it wonderfully, in addition to the serious stuff. Felton... woah. Exceeded my expectations, I can see why filmDraco is so popular. Everyone else was a treat, except I thought Bonnie Wright was a bit flat. Gorgeous cinematography and CGI, but not a memorable musical score.
Impossible for me to say whether someone who hasn't read HBP will be able to follow what's going on in the film, and I don't know where to rank this in my favorite HP movie list but I'll be seeing this one again 2x.