Finally finished Half-Blood Prince. Spoilerish discussion follows.
I’d have more sympathy for Harry jumping to the obvious conclusions about this if he hadn’t been hating Snape all along, in the sort of single-minded way that broadcasts that he is, in fact, wrong.
Now, if Harry had just been beginning to trust Dumbledore and believe he’d been wrong about Snape, and then Snape killed Dumbledore, and then Harry swung back around to Snape-is-evil with renewed vehemence–then I’d have sympathy for him. And, more, then I’d feel like I’d seen a believable bit of character arcing.
So what does Harry do? Ditches his girlfriend, ignores the DA, and declares that he must go off and fight Voldemort alone. Reluctantly accepts the aid of Ron and Hermione, but only after they pretty much shove themselves in his face.
(Headpalm) Dude, haven’t you been listening?
But then, we know that he hasn’t, judging by how his schoolwork goes when he doesn’t have someone (Hermione, the Half-Blood Prince, whoever) whispering the answers in his ear.
ETA: Now, if Ginny set out and reorganized the DA and set out with them against Voldemort–that would rock.
But all in all, yeah, I was disappointed. The pacing, the arcing of character, the fact that after six books Harry still doesn’t seem to have even begun to learn–all frustrating. Presumably he will learn in book seven–but character change and plot both are things that need to be arced over an entire story, not crammed into its final volume.