I really enjoyed HP5, though I wouldn't say it's my favorite (that's still #3 for me). I'd put it on par with #4. The pacing is problematic, and that affected my reactions to some scenes that should have been more powerful. In fact, and I can't believe I'm saying this, but I think it would have worked better if it had been a half hour longer. It needed a little more time to establish some key elements like the purpose and importance of Harry's Occlumency lessons with Snape, or the role that each kid plays in the climactic fight at the Ministry, or the impact of the prophecy.
But as noted, the acting is great, much improved over the last ones. I was quite impressed with Daniel Radcliffe (and, okay, I know I'm late to the party, but when did he actually get hot?? rowr!) and Imelda Staunton was *brilliant*. I also loved the girl who played Luna Lovegood. I thought Emma Watson was the weak link, though -- she came off kind of flat in a lot of her scenes. I've really liked her in the previous movies, so I don't know what's up with her now.
My favorite bits were the Dumbledore's Army scenes -- you really get the sense of these kids' fear of what's coming, but also their excitement at finally learning how to defend themselves and maybe even make a difference in the fight against Voldemort. Plus, Neville! Also all the teen-romance bits, often just throwaway things like a great reaction shot from Ginny when Hermione is teasing Harry about Cho Chang.
Best post-movie comment from one of my friends: "I love how Bellatrix LeStrange escaped from Azkaban -- by actually gnawing her way through the scenery."