I wanted very much to like this book; I am an avid fan of the series. I read it in one sitting, eager to add to the story.
Sadly, it seems to have been poorly plotted, written in haste, left unpolished, poorly edited, and rushed to the stores. I wish Ms Rowling had taken longer to produce it and taken more care. The smooth prose and the precision that have marked most of the earlier books are not evident here; the characters seem to be going through their well-worn paces without genuine passion. We are told that they are studying, learning, growing--but we see little of it reflected in the story. We are told, over and over, that Harry is obsessed with discovering what Malfoy is up to, but little result comes from this obsession. The characters do what is necessary to bring the book and Harry to a certain point, but there is little of the ingenuity and sparkle that enlivened even the grimmest moments in the early books. Much more than necessary of the plot is _told_ to us, rather than being revealed through the actions of the characters; and many characters that we have come to know and value--Neville comes to mind--seem little more than cardboard cutouts here. The famous death, which should have been an engrossing, tense scene of high drama, was really rather flat and surprisingly unaffecting. Compare Harry's reaction here to his reaction to another's death in _Goblet of Fire_ to see what I mean.
I would give the series as a whole a full five stars. But this book needed more work and more action and a good bit less talk.
I'm really rather depressed about it; I anticipated it for so long, and I wanted it to be wonderful; but I can't pretend that it is.
Of course, there is room in the plot now to make the series longer than the projected seven books if she wants to......