The trial. I love how Dumbledore's mere presence makes Fudge so incredible uncomfortable. You tell his ruse of moving the trial at the last minute was to prevent this very thing and it failed miserably since Dumbledore appeared to have suspected they would pull something like that.

I wonder if Mrs. Figg really could see the dementors. It sounds like her testimony was just memorized and she had been told what to say about the dementors. Or is that just her nerves? In a way I'm surprised that Dumbledore would encourage a witness to lie, even to protect Harry.

And of course we meet Umbridge for the first time.

I feel bad for Sirius being stuck in that creepy house, but I agree with Hermione that he is being selfish in being disappointed that Harry is going back to school.

And as to Ron becoming prefect instead of Harry. I like that. I think it would seem too expected if Harry had gotten it. Plus I think it's good for his ego not to be the winner all the time. And Ron does tend to be slightly more responsible than Harry. Or at least he doesn't get so angry and lash out as often as Harry does in this book. Or go digging into things better left alone.