Ron/Hermione: Ron's jealousy (regarding "Vicky") is very pronounced. I like how it is out in the open, not something he is hiding. Even if they haven't quite progressed to getting the rest of it to that point yet, they clearly both know how he feels.

Cho: Yesyes, she likes Harry. But why does the stupid girl think it a good idea to bring someone who doesn't want to be there? Does she need the support in order to be able to meet Harry? Doesn't she have any sensible friends?

The Weasley children: I like how Ron and Fred and George gang up on Zacharias Smith when he gets too pushy with Harry. And Ginny's imitation of Umbridge is wonderful. I can imagine the terror.

Fred and George really do know their stuff. Hermione's criticism is very unfair. Surely they don't know just "flashy" stuff if they can successfully create antidotes to all the horrible things they are making. And as we'll see in the later books, their inventions really do have useful applications.

Neville: His attack on Draco appeals to me. It is so effective because he has always been the meek one, never violent. Even his issues with his parents have always been very internal (shaking, being pale being the only external signs). This is therefore quite an astonishing development of Neville. I like it.

Trelawny: See, her hatred of Umbridge makes me like her more. It is as if we now share something. I see the same sentiment is expressed by Harry.

Sirius: Has he forgiven Harry only because of the DA? Did Harry have to prove himself? I cannot really think that, but the communication in the fire seems to suggest it. I like how proud he is, though.

I think Hermione is overreacting to the realisation the Sirius is living vicariously through the Trio. She is probably right that that is the case, but it has no impact on the sensibleness of the scheme as a whole.