Italics are impressions from my first read, when I did not yet know what was going to happen.
1) Accio Cloak! It doesn't work. Either this really *is* a special item, or the true owner of an object's wishes are taken into account by the summoning charm. I think the former is more likely.
2) The DEs assume that Harry is the one who set off the alarm. Why? Surely anyone Apparating into Hogsmede would set off the alarm? Do they think Harry's the only one who would try it?
3) Dementors. And once again the problem that Harry's Patronus will identify him right away. What was the other way Snape taught them to deal with Dementors? Why does not even Hermione remember it? Harry summons the Patronus anyway, with Ron and Hermione as his happy thoughts. Awww ....
4) ABERFORTH! And his goat Patronus. It just doesn't stop being funny .... Aberforth is there to save the trio, hiding them in the Hog's Head. And he doesn't take any shit from DEs either. He claims he was putting the cat out. *wonders if McGonagall/Crookshanks/Mrs Norris is secretly communicating with him in this way* I'm also wondering what house Aberforth was in. I'm sort of torn between Gryffindor and Hufflepuff. Also, how have Voldemort and the DEs not worked out that this guy is Dumbledore's brother?
5) The mirror. There it is! Aberforth bought it off Mundungus when we saw him in Hogsmeade during HBP.
6) But who sent the doe? Right. I've finally figured this one out. Damn, I'm slow!
7) Aberforth has been helping them. But he thinks it's all over and Voldemort's won. He believes it's time to cut their losses and run for it. He wants the good to win, and he's willing to do what he can to protect the people he likes, but he's lost his faith in the power of good to triumph over evil. His relationship with his brother was difficult for obvious reasons, but he does know Albus very well, and can guess the sort of mission he sent Harry on. What a wonderfully complex, bitter, lonely character. I look forward to seeing many fics about him.
8) Aberforth: "Secrets and lies, that's how we grew up, and Albus ... he was a natural." Maybe it's just me, but I really love this statement. I think I've finally got a title for my proposed Albus/Gellert fic.
9) Aberforth on Elphias: "Thought the sun shone out of my brother's every orifice, he did." *giggle* You know, I think I love Aberforth. He has a way of turning a phrase. He's terse but honest and he does not mince words or sugar coat his opinions.
10) Harry refuses to doubt again. He's made his choice and he's going to complete his mission or die trying. He knows Voldemort will never let him walk away, so he's got to do this thing and win or spend the rest of his life in fear and hiding as the world becomes a darker and darker place.
11) The painting of the girl. *sniff* They really were close, weren't they, Aberforth and Ariana? We now learn that she was assaulted (in some non-specific way which Jo leaves to our imaginations) at the age of six by Muggles for performing magic, and was driven mad. Her father avenged her and went to prison for it, but the family stayed quiet about the reasons to protect Ariana and keep her with them. Then, maybe while the brothers were at school, Ariana accidentally killed their mother. Imagine coming home to that.
12) Young Albus. He and Elphias came home for Kendra's funeral, and then Elphias left alone to travel. Then Gellert Grindelwald came, and Albus got so wrapped up in his new romance plans for world domination that Ariana became neglected. Aberforth confronted the two boys about it, and they fought, Gellert cruicio'd Aberforth, Ariana tried to intervene and was killed. None of them knew who was responsible, but Gellert fled the country the next day. Gellert calling Aberforth a "little boy" is a bit rich, considering they were only about a year apart.
13) Aberforth's education. Aberforth offered to drop out of school to care for Ariana, but Albus forbade him, saying that he'd take care of their sister. However, by the start of the next school year (Aberforth's 6th), Ariana was dead. So, did Aberforth go back to school? I think not. He was so bitter about his brother that he might have neglected his education out of spite. It makes Albus's crack in GoF about Aberforth being unable to read sound really quite cruel.
14) Harry remembers the cave. He believes that Dumbledore's anguished words while drinking the potion were the words he spoke to Grindelwald. But I'm leaving my options open for him to have been speaking to Ariana not to hurt the boys.
15) Harry vs The Greater Good. Dumbledore loved Harry, but was he still willing to sacrifice him for "the Greater Good"? I don't think I entirely believe that. I think he showed Harry everything he needed to see for Harry to make his own choice about whether or not to sacrifice *himself*. Dumbledore learned from the Ariana incident that we are all flawed and fallible and that we are only as good as the choices we make.
16) Ariana shows them the way. I like that Ariana is the way into Hogwarts. I feel like there's a symbolism going on here that I haven't quite completely understood yet.
17) NEVILLE!!! So. Much. Love. He is my hero. I don't think I've been so excited to see anyone this entire book.