I couldn't help noticing that Hermione actually had properly bushy hair for at least one scene. Can't remember if it still was at this point in the books, but I know her hair's been far too nice ever since her make-over in GoF. Anyway, it was there in HBP. Granted it was during potions class while she's furiously stewing away over a boiling pot (or had just had it blow up on her, forget which exactly), but it was still there. :D
I LOVED Luna in this movie! She was just as loveably wacky as ever, and she was definitely present in the movie (not quite as much as five of course, but still quite a bit).
I thought it was a bit odd that Luna "replaced" Tonks toward the beginning by being the one to find Harry in the train. I loved it, of course, since Luna is still one of my favorite characters ever, but it was still odd.
Speaking of my favorite characters, what on earth happened to Neville? I think his biggest part in the whole thing was serving at Slughorn's party. He also showed up in potions class (which I distinctly remember him NOT taking in the books), but now that the movie's over, I'm actually glad of that, since it gave him a little extra much-needed screen time.
Also, what on earth happened to the whole show-down fight right before the end? Harry still got to chase down Snape, call him a coward and try to sectum-sempra him (though Snape never said not to call him a coward. I kept waiting for him to say it and he never did. :( ), but full-out fight as the death eaters tried to get up to Dumbledore was completely cut. Instead, after a dramatic appearance in the vanishing-box-thing, they apparently just strolled over to the tower to join Draco. (The people behind us were very not pleased, and decided that this made it the worst HP movie of them all... yeah.)
I can't entirely believe it myself, but I seriously spent just about the whole movie feeling incredibly bad for Draco. The poor guy was in way over his head and Harry really wasn't helping matters any.
I don't know if it's because the last book's out now and I know what really went on, or what, but I could pretty definitely tell that Snape was ultimately on Dumbledore's side (and especially didn't want to kill him or anything) just by the way he reacted to certain situations. He genuinely looked like he didn't want to kill Dumbledore, and again, I felt so bad for him.
His exit seemed very different to the book for some reason. I'll have to compare it sometime, but in the book, he ran off with Draco after his final skirmish with Harry, whereas in the book, he leaves with Draco and the death eaters in sort of a casual victory or something, though stays behind a bit to have his confrontation with Harry who kept trying to cast stuff at him.
Someone involved in the movie apparently had a thing for burning buildings or something. After the bridge randomly got destroyed at the very beginning, both the Weasley house and Hagrid's house were burned by death eaters throughout the movie, and both times it seemed a bit pointless other than to add drama to the scene via a burning house.
The romantic storylines definitely added plenty of fun (and some comic relief), and though they didn't quite mesh tone-wise with the darker plots going on, they were still a lot of fun. Ron's girlfriend (Lavender? already forgot her name...) was seriously amazing, and Ron was pretty hilarious under the effects of a love potion.
I wasn't so sure about the Harry/Ginny romance plot, though. At first Ginny was shown happily paired off with her boyfriend, then a bit where she's late to Slughorn's party and it's commented that she'd been fighting with her boyfriend again, and that's the last you hear of that relationship. Next thing you know, she's fairly aggressively trying to flirt with Harry (trying because they keep getting interrupted), and suddenly, in every single scene with the two of them from then on, I could seriously feel the Harry/Ginny pairing being pushed at me with a whole lot of force.
On a much less serious note, I happened to wear my black converse to the showing tonight, and I kept getting distracted by noticing that Harry was also wearing black converse throughout the whole movie. There's definitely something about wearing near-identical shoes to the main character, especially when it was accidental.
Finally (yes, finally!), before the movie even began, one of the trailers shown was for the upcoming Twilight movie. Now, I'm not at all a Twilight fan for a variety of reasons (though I'm very amused by the fact that Twilight vampires SPARKLE), and I think it's very safe to say that at least quite a few people in my theatre tonight were not exactly fans either. Not a whole lot of people seemed to be taking the trailer too seriously, though I think most recognized it as Twilight right away. It officially became memorable, though, when, somewhere in the trailer, Edward says something about how he has to leave and can never see Bella again. At this, a random guy in the audience lets out this mock-tortured "AAAGGGGHHH!" and a lot of the theater broke out into laughter. :D (Yeah, okay, so it was a fairly active audience this time around, but hey, it was fun.) There were other random reactions to the Twilight trailer as well, some more serious than others, but that one kinda stood out.
So yeah, that sums up most of the reactions I can remember having to the movie, or what I remember particularly standing out. I think I have a chance to see it again in a couple days, so I look forward to getting the perspective of a second viewing. Beyond that, the movie definitely has me excited for the last movie(s) to come out, whenever that is. :)