Well, it actually won't be too badly overanalysed yet, as I'm attempting not to spoil any plot twists. I may come back and do a follow-up, complete with brutal spoiling, at a later date. I do, however, spoil the big death from the previous book, in case anyone's somehow remained unaware of it.
The fifth Harry Potter book did not quite work. On first reading, we thought "that was pretty good". After a little consideration, we admitted that it perhaps dragged a bit. Eventually, it came to our attention that large tracts of it were rather boring, in particular the first 200 or so pages loitering in the Black household, and that the death of Sirius was awful.
The sixth book, I'm thrilled to say, is a substantial improvement from that. Things actually happen, relevancy is obtained and much drama is wrought upon everyone. One thing that does remain from the fifth instalment is the inclusion of the pains of puberty, but it changes form from Harry's relentless capitalised tempter tantrums to the immortal question of "Who's going out with who?", which isn't quite as irritating, although it does go on a bit and some of the couplings are a bit bizarre.
Despite my annoyance with the sense in book five that nothing that significant actually happened, the "prophecy" revelation from that volume does play a substantial role here. It then pushes itself onwards to bigger and scarier things. It is hard not to be impressed how well all this fits together. A lot of things from earlier books are explained and drawn into the plot seamlessly, and whether it was planned all along or Rowling did make it up as she went, it works. Coming into this book, I was worried it would simply be "the set-up for the end", but it turns out that book five was the set-up volume and this one is just the first half of the headlong rush for the finish.
The downside of this, of course, is that a lot seems unresolved. There are many things that we will have to wait for book seven to see the anwers to. It's hardly a complaint, I know ("Author manages to make readers want to read sequel. That bitch."), and there are enough things that both start and finish in this book to make it satisfying, but the wait between books will seem even longer.
Negatives, you say? Well, luckily, I'm good at finding things to complain about. Apart from the wide-ranging and often quite random scattering of hormonal angst, I only have a few petty grievances. Like, there's an effort at the end to obtain a certain "It's all futile" effect, which skates dangerously close to "nothing which just happens matters". Actually, if I could change one thing, it might be the title. I think putting "the Half-Blood Prince" front and centre kinda skews the reader's approach to the sub-plot. I don't know what I'd replace it with, but still.
I may return in a few weeks to pick apart specific plot points, but for now I just wanted to give a solid recommendation. If you disliked book five and were reluctant to give book six a try, I think it might be worth it. Thank you.