First of all, a short intro from me. I'm Caroline from Australia, directed here by nesmith. I enjoy the books, but am not involved in the fandom and I am indifferent about the movies. Anyway, onto my "analysis" of The Half Blood Price.
I felt quite let down by HBP. It didn't feel as exciting as the other books and I didn't think there was a need for all the romances. I am definitely not a shipper, and I couldn't care less about who's dating who. I'm more interested in the fight between Harry and Voldemort, which really didn't come to much in this book. Usually I can't put the book down, but I could this time.
That's not to say that it was a complete waste of time. I felt that it was more informational than I would have liked it to be. The background on Voldemort/Riddle was probably essential to the completion of the series but I would've liked it if we found it out in a more exciting manner.
I was surprised that the Half Blood Prince was Snape, as I thought it was the obvious candidate - Voldemort. I don't know what to think about him being on the other side yet. My mum was very disappointed that he is working for Voldemort, since it was that 'good' side to him which made him interesting. I'm not sure about it because I loathe his character anyway. I loathe Draco less because he couldn't kill Dumbledore. I actually felt sorry for him.
The usual hatred between Griffindor and Slytherin was not as present as it used to be. There was less of the strong emotions of fear, uncertainty, hatred and anger; and more jealousy, 'love/lust' and a general feeling of indifference (if that's the word I'm looking for).
I found out the Snape killed Dumbledore before I had read it, and I was not emotional over it was I was when Sirius died. I think it was because there were hardly any powerful emotions felt by the protagonists. When Sirius died, Harry was so angry and upset and I felt that too, even though I was spoiled before reading it. It was only Hagrid's reactions that made me feel a little bit teary. Actually, I think Dumbldore's death was very calm.
I think the dominance of relationships was what really brought the experience down for me. Bill/Fleur, Harry/Ginny, Ron/Lavender, Tonks/Lupin, Ginny/Dean and to a lesser extent Ron/Hermione even though that's been foreshadowed throughout the whole series. The lack of action I could cope with, because the information given almost made up for it (I was expecting an action-packed book).
As my mum said, it was really half a book. It felt that nothing was really resolved. Here's hoping that the next book exceeded expectations as Order of the Phoenix did for me.
I read (somewhere, I can't remember where), that JKR does consider books 6 and 7 to be more of a two-parter, and that she was intending to answer questions in these two books rather than raising a bunch more, but the real resolutions wouldn't come until the last book.
Dumbledore's death really had to happen somehow; it's the archetypical thing to do in the journey of a young hero coming into his own. You have to get rid of the mentors somehow.
As for the relationships, this is a young adult book, and they are a bunch of 16-year-olds cooped up together; I don't think it would be reasonable for nothing to happen along those lines. :)
You know, I didn't think about it while I was reading the book, but now that you mention it, it does feel as though Book 6 was only meant to be the first half of a two-part series. I remember getting to the end of the book and going, "huh, what? that's it? Where's the resolution?" I didn't feel disappointed, though; it's just made me very, very eager to read Book 7, even though I'm dreading it because I know a lot of bad must happen before it ends.
I will be honest and say that of all the characters I expected would die before the series was over, Dumbledore was at the top of the list, for the reason you listed and more. It just seemed highly unlikely to me that someone in his position would be able to get through the books alive and unharmed. In fact, I think I knew what was coming when he showed up at the Dursley's house in the second chapter and Harry first noticed his hand. It was like the first indication that Dumbledore was human and very much mortal. I think the injury came as more of a shock to me than his death did. And, like you said, you have to get rid of the mentors somehow, or the heros won't learn to shine on their own. ^^
I started a really long comment on the relationships, and then decided to turn it into a thread of its own. I was glad someone other than Voldemort was the HBP as I've always wondered about the Death Eaters and how they came into existence. I can see now how Snape's jealousy led him to follow Voldemort, and I can imagine the attraction for certain personalities to being evil. I think Draco's character provided some insight into the fact that no one starts out a killer, that takes time and pushing. Whether or not Draco will stay an innocent remains to seen, as he is still Draco, and he does enjoy being cruel.
I'm still hoping for the redemption of Snape - I just keep thinking of Dumbledore demanding that Harry follow his orders no matter what would happen...
Now, I can't find the link, but someone had written a very thoughtful essay on Snape/Draco/Unbreakable - and how Snape had to play a very very fine line between keeping Draco dafe, fulfilling Dumbledore's orders, and keeping his cover with the Death Eaters...
We all know he's great at Occlumency - it's mentioned quite a bit in the book. I think he's still hiding something.
But then again, I've also read thinks JK Rowling has said about Snape, and I'm hoping she doesn't hate him enough to take away his chance at redemption.
I think I'm reserving all judgements until I read the last book. I think it's too easy to jump to conclusions...