OMG, it was SO GOOD.
Some random thoughts/observations etc (these are very scattered, I am still trying to get my head around it all).
x. DUMBLEDORE??? What the--- ohmy. I cried. I didn't cry when Sirius ("Serious" Black ;) - loved that first chaper!) died, but I was devasted that Dumbledore was killed! And by --
x. SNAPE !! Dumbledore trusted Snape SO MUCH. Constantly defended his actions, convinced that he had renounced his evil ways for good. Oh. That second chapter, about Narcissa & Bellatrix & the Unbreakable Vow sent shivers down my spine. It still haunts me.
x. I am reading theories that Snape was acting on Dumbledore's wishes, that Dumbledore wanted him to kill him in keeping with the act of being Voldemort's most loyal confidant... but oh, while they are good, I just can't quite believe them. Maybe I need some time for them to sink in though.
x. And when Harry had to keep pouring that potion into Dumbledore's mouth... oh :(
x. Weren't we meant to find out why Harry having Lily's eyes was so important though? I'm so sure that was going to be in book 6, looks like it will be book 7. Never mind :) [edit: upon checking the MuggleNet website, the 'facts' are for books 6 AND 7.]
x. Snape - the Half Blood Prince. Interesting. Like most people, I never thought of him as a possiblity -- I always thought the HBP would be a "good" character, as such.
x. Horcruxes - love the idea. JK Rowling's imagination never fails to amaze me.
x. Draco - didn't really surprise me at all that he had turned so deeply over to the dark side/becoming a pawn in Voldemort's plan - it's only natural, considering both his parents are Death Eaters (I think? Was Narcissa a Death Eater? Her sister was....) and especially after his father was placed in jail.
x. R.A.B. --- ohhhh, I can't wait for Book 7 (I really like the theories that are emerging that it is Regulas (sp?) Black - Sirius's brother who became a Death Eater but then tried to turn back -- to me it's like a piece of Sirius will return in some form).
x. Speaking of book 7, I think I like the idea that Harry (&co) won't be returning to Hogwarts (as far as we know) -- I like the idea of the story not being hindered by classes & homework & Hermoine telling the boys off for not studying more ;) Not to mention that with Dumbledore gone... as plathsrevenge says, it wouldn't be Hogwarts without him.
x. I think it really highlights how huge a task this is for Harry... it is about life or death now.
x. The relationships -- well, all the fanfic shippers are going to have a field day with this, I'm sure! I am happy that Harry & Ginny finally got together (although sad they broke up at the end, although I can completely understand why Harry did it - he always had the feeling he was going to be alone - a marked man - and to have a relationship was just too dangerous for the other person - something he has always stood firmly against from book 1 (ie, warning Ron & Hermoine not to put themselves in danger, facing Quirrell alone in The Philosopher's Stone.
x. Hermione & Ron - I thought their jealously at each other's relationships/partnerships was cute ;) There's always been underlying jealousy there, right from what, book 2? - it's only natural that in Book 7 they finally admit they have feelings for each other... well, that's my opinion anyway.
Oh, I have so many more thoughts swirling in my head right now, but I am struggling to write them in a logical format (as you can probably tell), so I think I might write more later about it... but goodness, this book was so wonderful, and I am desperately longing for #7!!!
(ugh... this entry was horribly written. apologies.)