Italics are impressions from my first read, when I did not yet know what was going to happen.
1) Luna is quick on the draw. She beats Harry to stunning Alecto. Well, Harry's having scar issues, but still; Luna managed to beat Alecto, too, and she had the element of surprise working for her. I guess Luna is never really surprised by anything. I forgot she was still under the cloak. She's still awesome in this scene. "Oh, look. They're pleased!"
2) Voldemort decides to check on the locket first. Harry is lucky again. This buys him about another half hour. Good thing Voldemort made the locket hard to get to. Who is going to drink the potion this time? It obviously refilled itself between Regulus and Dumbledore, didn't it? Ah, okay. The potion turned clear for him. Nice.
3) Amycus arrives. Presumably Alecto's summoning of Voldemort was also passed around the rest of the Death Eaters as well.
4) But how did McGonagall know where to go? Is she keeping an eye on Ravenclaw tower, based on Flitwick's information? She later tells Snape she heard a disturbance, and I know Amycus was making a racket, but it's late at night and her rooms are in a completely different part of the castle; there's almost no way she could have heard him. My McGonagall is Evil senses are tingling. We're on Ch 30, and this is the first time we've heard from her in this entire book. What the hell has she been up to? She almost looks like she's helping the Carrows here, and has done nothing to assuage my suspicions thus far. As soon as Harry felt a rush of affection for her, I was *sure* my theory was about to be vindicated. *sigh*
5) "Where do vanished objects go?" They cease to exist. Weren't the kids vanishing kittens at one point? :(
6) Cruciate. Finally, we get the verb form. :p Yeah, I'm a linguistics dork.
7) Harry Crucios Amycus! For McGonagall. Holy shit! Why, WHY did Jo decide to do this? Is she slapping us in the face with "Harry is a grey character"? He could as easily have stunned Amycus with the element of surprise he had. The Imperius curse is one thing; Harry did not intend to harm anyone by using it. But this is something else entirely. I'm pretty upset that Jo went there. Especially since, in the next chapter, Harry merely stuns someone who tries to *kill* Hermione.
8) McGonagall doesn't bat an eye. She's startled to see Harry, but says not a word to him about his use of the Cruciatus curse. In fact, she turns right around and uses the Imperius curse on Amycus. And she calls Voldemort "the Dark Lord", which is a Death Eater thing, isn't it? She has so got to be evil! It's proof that she's been working for herself all along! *sigh* OK, how about this? She's still being all ambiguous, and decided to come out on Harry's side once it looked like he might win? I *want* her to be evil! I think Jo missed a fantastic opportunity for a plot twist here. She tells Harry they will fortify the school against Voldemort while Harry searches. Now that the Carrows are taken care of, there's only Snape to deal with. And he's on our side.
9) McGonagall conjures multiple patronuses. Patroni? We've never seen this done before. Hers is a cat, of course. Like Umbridge.
10) McGonagall vs Snape. I was so sure a battle between these two counterweight characters would hint at opposite loyalties. *sigh* Instead, McGonagall attacks and Snape defends, but does not try to hex her. He calls her by her first name as well. He doesn't do this with many people, does he? Usually he refers to his colleagues as "Professor". McGonagall calls him a coward, as Harry did at the end of HBP. And apprently he's learned how to fly. Why the hell don't more people learn to do this? It seems handy. McGonagall watches his escape and *still* has not ordered the school fortified, despite the fact that she *knows* Voldemort is on his way. She's also gone and put Harry's possible protector to flight. Nice one, Minerva.
11) Slughorn stayed. He was only convinced to teach in HBP because he thought Dumbledore could protect him once he declared his loyalties by accepting the job. I'm really surprised to see that he's stayed on.
12) Finally, McGonagall makes a plan. The heads of house will fortify the school, and gather their students in the Great Hall for evacuation. Surely the 7th floor corridor would be better? McGonagall states that any student of age may stay and fight if they wish. She gives Slughorn the option of leaving with his students. Slytherins are definitely the weak link in the castle's defences.
13) Flitwick: "Seen it? Nobody has seen it in living memory! Long since lost, boy." Then I guess you should ask someone about it who's not living, shouldn't you?
14) Filch has been complaining about Peeves for about a quarter of a century. I guess we now know how long he's been at Hogwarts.
15) McGonagall's walking suits of armour. *sings* "Substitutiary Locomotion..."
16) The twins got in touch with the Order. How? Patronuses? Can they really travel that fast? Geez.... The rest of the old Quidditch team is there, too, even the ones who predate the DA and who we never heard were in the Order. Gak! I've just been severely bunnied ....
17) Dean reaches for Luna's hand. It's sort of "awww", but I don't really buy Dean/Luna at all. I just can't see it. Also, we don't know that Luna is of age yet. I mean, she's a sixth year, so she probably is, but we don't know when her birthday is. Ginny is underage for sure, but there's no getting rid of her when the rest of her family is fighting.
18) Percy? WTF?! OK, how in God's name did *he* know where to go? And how did he manage to choose this very moment to declare his loyalties? I guess id he's been in contact with Aberforth for a while ... but how did he know Aberforth was the man to go to? It's all a bit ... hmmm .... He makes up for his past arsitude it in style, though; I'll give him that. Oh, f***! Everyone's getting reconciled before the battle. They're all going to die, aren't they?
19) Remus is suddenly waving baby pictures. My brain is imploding. What the hell is going on here? Can we have old Remus back? Please?
20) Mrs Weasley pushes Fred aside to hug Percy. *brain splodey*
21) Ron and Hermione "said something about a bathroom". OK, I know where my brain went the first time I read that. Quickie before the bloodbath, kids?
22) Voldemort is at the gates! Dun dun dun....