Bode, obviously. Both his death and the reason for his madness is revealed. That side of the story now begins its second half, as Voldemort is told not just anyone can retrieve it. We are, of course, also told why Podmore ended up in Azkaban (thank you, Hermione). I like how that mystery had been allowed to disappear from the radar, and is now brought up and tied together with the rest.

And I like how the Murtlap essence thing makes its way from Hermione telling Harry to Harry telling Lee Jordan after detention with Umbridge, to solving the earlier introduced problem of Fred and George's Snackboxes. It is neat.

Firenze's observation that another war is coming, while not a terrible surprise, is accurate.

And then there is the end of the DA, of course. I suppose the good thing is that it teaches them to make the room entry-proof in the final book.

Dumbledore's comment that Fudge will wish that he had never dislodged Dumbledore from Hogwarts is interesting. What does it refer to? What does he do, specifically? Also, it reminds me of Star Wars (if you strike me down...).

Themes: the half-breed problem is again present. We are shown how Dumbledore works against it, and how it is used to undermine Umbridge. But also how it is in reverse: that Firenze must suffer from the disapproval of his own people as well. And of course there is Dean's unthinking assumption that Hagrid "breeds" centaurs.