Note: No intentional spoilers for book 6 here, but details of previous Harry Potter books are included.
Honestly, seriously -- I had no intention of falling into Potter-mania. I have long loved Ursula Le Guin's Earthsea trilogy, in good part for its portrayal of a young man coming of age and into his own power; and I viewed the Harry Potter phenomenon as a shadow of what Le Guin accomplished. While I still hold to that, I confess that Potter has worked a charm on me (or is it a jinx? I'm still not sure). My young children not being up to reading them themselves, I began reading the Harry Potter books aloud to them, after enjoying the movies with them and wanting to know more about the wizarding and Muggle worlds Rowling has created. While it's fair to say they're more enraptured than I, I nonetheless somewhat impatiently waited in the queue in our family for a copy of Harry Potter and the Half-Blood Prince to work its way to me. Yes, I read it for my own enjoyment before starting to read it aloud to the snolfs. And I stayed up well past my usual bedtime to finish it.
Much of my interest in the Potter books centers on the pro-freedom themes many find in them, in addition to all my childrens' ongoing interest. As was the case with the three Matrix movies, many pro-freedom individuals find things in the Harry Potter books that lead them to think J.K. Rowling is a libertarian author. Does Half-Blood Prince continue in that vein? Yes, to some degree.
The action begins in the British Prime Minister's office, with a visit from Fudge. The exchange between the two politicians is a great, if somewhat understated, portrayal of typical ruling-class chatterers -- playing the blame game and CYA in fine form. Later in the book, Rowling pegs the true nature of tyrants, offering tidbits that freedom activists would do well to remember. Fred and George Weasley also provide an object lesson in the value of humor. Of course, Harry continues to mature, learning to rely upon himself more and more, while also learning important lessons about balancing that self-reliance with relationships with others. Rowling is arguably at her best in her characterization of the fits and starts that are part and parcel of teenagerhood. So, there's undoubtedly solid stuff for freedom-loving people in Half-Blood Prince, but I think that anyone who believes Rowling is a libertarianish author playing her cards close to the vest will be sorely disappointed when the Harry Potter story is all told.
As is inevitable in a storyline this sprawling and complex, some threads are left dangling while others are picked up. Learning more about Harry's nemesis Voldemort fills a good portion of Half-Blood Prince, setting up the confrontation foretold by the prophecy revealed in Harry Potter and the Order of the Phoenix. Romance suffuses the air at Hogwarts -- both genuine and potion-derived -- and is fairly realistically addressed. Some nice surprises lurk here, too. While Harry and his close companions show maturation, others who'd shown progress in Order of the Phoenix seem forgotten in Half-Blood Prince. The D.A. also seems inexplicably abandoned, much to my disappointment.
Some elements are ever the same in the Potter world, so readers get the regular doses of Malfoy, Snape, Quidditch, and Hermione's and Ron's bickering amongst themselves and with Harry, whose suspicions they discount. A nice difference is deeper, more mature interactions between Harry and some adults. The obligatory mysterious article that isn't what it seems is here, too, along with the appearance of a new wrinkle in Harry's fight quest to defeat Voldemort. The strange wording of the prophecy seems crucial there ...
The Half-Blood Prince does suffer a bit from "penultimitis". While it does a capable job of getting everything into place for the final book, in doing so it doesn't pack the punch that, say, Prisoner of Azkaban did for me. A good portion of the Voldemort back story could have come sooner; and the climax of the book is a bit too formulaic for me to take at face value. Oh, and if you've successfully avoided all spoilers that reveal who dies, you'll probably want to avoid reading the title chapters at the front of the book, because they give it away, too, although quite subtly.
Much to my stepsons' horror, I declared upon finishing Order of the Phoenix that the Harry Potter story is a "pretty good story, adequately presented". Rowling's writing is nowhere near the craft of other fiction or fantasy greats, and the Harry Potter universe is riddled with inconsistencies (perhaps the most blatant one being the erasing of some Muggle memories involving the existence of a magical world, but not all of them, as Muggles can have children with magic powers). I stand by that view still, and say that it's a testament to the goodness of the story that I'm not simply willing to continue reading -- I'm among those trying to wait patiently for the next movie, as well as for the story to close.