So, picked up the book a few days back (sadly, bought it before I found out that I might have been able to get it by redeeming customer points at local petrol station) , finished reading it. My thoughts?
On the book overall: A generally better read than the previous one. OotP, while containing important stuff, and a few good moments, and Luna Lovegood who amuses me to no end, was a bit too much work to read. This one, by contrast, was a much more fun experience.
On Draco Malfoy: Ha! Finally, I am vindicated. The abundance of fanworks featuring Draco Malfoy as either a shining paragon of virtue, or the Real Big Bad of HP never cease to amaze me. I dunno, I honestly find it a bit hard to see Malfoy as anything but a spoiled rich kid, who is certainly unpleasant and does a decent job of antagonising Harry... but throughout the series, I've never seen any indication that he's anything more than that. Seriously, where are some of these people getting this? His purpose in the overall plot (as far as I can tell, feel free to argue the point) is to make the real villainy stand out- Draco's little schoolboy pranks and campaigns against Harry just make Voldemort's actions much more evil by contrast. The idea of Draco really amounting to anything big is pretty much incomprehensible to me.
On Ron/Hermione: Hm. Could go either way. Will not be surprised if they actually become a couple in the last book, but I wouldn't say it's graven in stone.
On Harry/Ginny: Decent. Honestly wondering if this is the end, or Rowling will have more of this in the next book, despite the whole Spiderman moment at the end.
On Dumbledore: Now you see, this is how Sirius should have gone. We really got to see the relationship between him and Harry build, got a sense of just how good he was... and then he died in a well-handled way, as opposed to the whole thing with the curtain. Also, am quite fond of his entire speech on the prophecy not really mattering to Harry- makes the anticlimactic revelation of it's contents at the end of OotP less annoying.
On Slugthorn: Oh my goodness, a halfway decent Slytherin? About bloody well time, JKR. Also, nice little shell game with him, Snape, and the Defence against the Dark Arts post.
On Tonks/Lupin: Eh. The couple itself is okay, but the pairing was not very well done. It really wasn't so much a side-story as a plot device to confuse the readers. For a short while, I was wondering if Tonks was the one who had passed the necklace in the girls bathroom.
On the Abridged History of Voldemort: Not bad. Useful to know, and helping to build a better picture of the villain of the series.
On Snape: Hokay, this one is... interesting. Not entirely sure about the Half-Blood Prince stuff- when you get down to it, you could probably excise pretty much every mention of that from the narrative, and the story could proceed okay, which is kind of odd considering it's the sodding well title of the book. As for the whole 'Yup, he's definetly evil' bit... I dunno, I'm, finding it pretty hard to believe, actually. If nothing else, what was up with that whole 'look of hatred' he gave Dumbledore at the last- we've never had any indications that he felt anything more than periodic irritation towards Albus on account of his not getting the DaD job. On the other hand, if one assumes that he's a White Hat, and deep cover within the ranks of the Death Eaters, then it makes perfect sense- that hatred is because he's being begged by Dumbledore, the one person who seems to truly trust him, to kill him. This also explains away his sudden rage at Harry's calling him a coward. Maybe it's just my comics background showing through in this- that's a genre wherein 'deep cover' can extend to being killed, brought back from the dead as an undead assasin and crashing a helicarrier into the sea thereby killing hundreds of people on your side, before finally breaking cover. Next to that, offing Dumbledore seems somewhat mild.
Also, I must say that I do like how Snape pretty much bitchslapped Harry magically during their short fight. The Boy Who Lived has uncommon talent in DaD, as well as the freshness and unpredictability of youth, but head-on, against a seasoned veteran wizard? No contest, and something that's nice to see after the hard-to-explain showing of Dumbledore's Army against the Death Eaters in the previous book (at least this time, Ron and Hermione got through it because of Felix). Then again... hmm, I wonder if the Horicrux theory might help explain that as well...
On Horicrux: Huh. Not exactly surprising, but a decent plot device. That's quite a bit for Harry to do from now till the end of Book 7- unless JKR writes the destruction of some occuring off-stage in-between books, which is a bit unsatisfying. Then again, we have the mysterious R.A.B out there, so there's always that.
On Dobby/Kreacher: Muchly amused. I think they could rate a short story all of their own- "The misadventures of Dobby and Kreacher".
On the ending: Hm, I'm honestly wondering what on earth Harry's going to do next? His resolution to track down the rest of the Horicruxes seems a little bit niave, seeing as how he's stonewalling even the Order of the Phoenix on their existence. I mean, all he has in the way of resources is Dumbledore's lessons on Voldemort's history, his account at Gringotts, Ron, Hermione... and Kreacher and the resources of Black mansion, I suppose- not very impressive considering the task ahead of him.