As for Dumbledore dying, I was sort of shocked. When I heard someone else was dying in this book, I expected it to be between Lupin, Ron, Hermione, Neville, and Dumbledore. But to see it played out that like...just, wow. Hopefully he had passed on all the information to Harry that he had known, all the information Harry needs to find the last few Horcruxes. I nearly cried, I'll admit it. (blush) Dumbledore was easily a favorite character, and you sort of expected him to stay around just because he was so smart and resourceful. He became a necessity to Harry, and to yank that away from him...well, we'll see what happens.
As for Snape, well, I was really starting to hope that he was on the good side. Dumbledore being so convinced about him, no matter how nasty he could be, it made me hope that Snape was good. But within the first couple chapters of the book, I realized that I was wrong, obviously. I never expected him to be the Half-Blood Prince, but I should have guessed with it being Potions that he was so good at. There were many hints, I just never picked up on them.
So, on to Malfoy. It was not surprising when I read that Voldemort had given him a task to do. In this book, he went from being a simple bully and Dark Arts fanboy to a real tool being used by Voldemort. Scary stuff. I'm pretty sure had Snape been prevented from getting up to the tower, Dumbledore would have lived. Malfoy didn't have the guts to kill Dumbledore.
Hermione and Ron as a couple is seeming more like a real possibility instead of just a concept being hinted at. I've known since book four that Ron liked Hermione, it was just the other side of it that wasn't fully revealed until this book. I thought it was a nice touch to add the backstabbing, because real teenagers do stuff like that. I now officially love the word "snogging".
Harry becoming Captain of the Quidditch team wasn't a surprise. The fact that he got an Outstanding in Defense Against the Dark Arts was not surprising either.
I loved the fact that they learned to Apparate. Very useful, and very cool.
I loved the Harry and Ginny thing. I was hoping he would start to like her. It was sad that they had to break up, but it was certainly necessary. I agree with whoever said it reminded them of the Spiderman speech. Totally cheesy.
I don't know about the idea of Harry not going back to Hogwarts. Maybe he's right about needing to just go and search out the Horcruxes, but I would think that another year of study could help him learn some more. Ah, what the heck, leave school! Good idea. Seriously.
There are still questions to be answered in the next book, and I can't wait to read the last one.