I too was suprised that Snape killed Dumbledore. I thought Snape would turn out to be a good guy. He still could I suppose, but it would be a stretch to say that Dumbledore was telling Snape to kill him because going to die anyway with through Snape's occlumency skills. The only evidence for this may be how he handled Harry when he was running out of the grounds w/Malfoy and the death eaters. Perhaps, Dumlbedore had to die and Snape killed him to gain Voldemort's and the death eater's trust. Doubtful.
I think there has to be another adult character to help Harry. It could be that he has come of age now for the last book, but Harry is lacking in wizarding skills. It would be lame for him to take out the horcruxes and Voldemort with Love. So I think to make it good there must be an adult or group of adults, but there is no adult character left really that the reader has much attachment to. Lupin perhaps. It is a children's book, however, so the child must be heroic. I just don't think it is as good w/Harry wizarding it up himself even w/Hermione and Ron. Hermione seems to be the best wizard at this point.
I thought cheating and laziness on the part of Ron and Harry are bad examples as far as children's books go. Hard work makes a good wizard not Harry's amazing ability to love his dead parents and Sirius.
I was also suprised that the Half-blood prince was Snape. I guess I'm just dumb and should have seen that coming on reflection, but I thought it was Tom Riddle's book. That was a pretty good twist.
So, Snape is super powerful and is really on Harry's side, thus he becomes the guiding adult.
Probably not, but the kid wizard can't do it himself or the book will suck.
