I think the best way to describe this book is relentless. So many places where I felt the action pulling me forward, no chance to breathe or to rest or, especially, to relax -- no battle is without consequences, every success followed by a dire challenge. The last third or so of Order of the Phoenix had this same feeling, but in this case it was almost the entire book. Given the difficulty of Harry's task, I think that tone is appropriate. When the first battle ended with the deaths of Hedwig and Mad-Eye and the maiming of George, I figured we were in for a bumpy ride, with not many punches pulled.
-- The Trio and their quest. I really liked that it was difficult, that Ron and Hermione had doubts, that Harry didn't always know what direction to take. It made it seem more real. I loved Ron finally facing and standing up to his insecurities, and I think the way he became so much stronger and more thoughtful was well done. Also, the fact that the three of them could still face almost every situation with humor. The moments of levity never felt forced, and they often came at just the right time to lighten the tone.
-- The moral ambiguity of Dumbledore. He's always been painted as just a little too perfect, although we started seeing hints of this as far back as book 5. The image of him as a power-hungry youth is just shocking enough, and yet it still fits the character. A neat bit of retroactive development.
-- The redemption of Kreacher. This is quite possibly the last thing I was expecting, but it was marvelous.
-- Neville. Do I really need to say anything more?
-- The resolution of the wand puzzle. Another twist I was definitely not expecting, but I thought it was clever, and handled well.
-- Harry gets a happy life at the end. If anyone has earned such a reward, it's him.
-- Draco. I had been hoping for more moral ambiguity on his part after his confrontation with Dumbledore at the end of the sixth book, but here it turns out that he's nothing more than the self-centered all-talk bastard that he'd always appeared to be. Disappointing.
-- Dumbledore explains it all, afterlife version. Was there really any important information in that conversation that Harry, and by extension the rest of us, hadn't already figured out? It went on for too long and broke up the action at the climax of the story.
-- Snape. I always figured that he was on our side and had killed Dumbledore on orders, but a secret love for Lily Potter as his reason for his loyalty? I guess I buy it, but it also seems a little hackneyed. Although it does put an interesting spin on the reason that Snape chose that particular moment as his worst memory -- it wasn't about James and Sirius tormenting him, it's because he called Lily a Mudblood and thereby drove her away. I'll need to mull over this some more, I think. I'm going to have to go back and read it again anyway; I'm sure I missed a lot of details rushing through the heavy action sections.
Still a little stunned over the deaths of Fred, Lupin, and Tonks (although I think Dobby's death was easily the saddest). Even more stunned that Hagrid made it through. Also I am now free to say that I stumbled over the fake "Hermione dies" spoilers a couple of weeks ago (I locked down my community reading a little too late). I had always taken the attitude that the most widespread spoilers were probably fake, but neither did I assume that this meant Hermione was untouchable; I got pretty scared for her during the Bellatrix torture scene. But once she made it out of there alive, I figured she was probably safe. I am very glad I was right.
Overall, I give it a thumbs-up. The third book will probably always be my favorite, but I liked this very much.