OK, I only have a minute but I'll come back later. I'm about where you are in the book.
Yes, I, too, really like Luna Lovegood. What do you think of her name? Since most of Rowlings' character's names are somehow indicative of their personalities, I'm wondering what we may discover about her later. I'm thinking she could be a love interest for Harry if Cho doesn't pan out. She seems to have some intuitive wizarding powers that I haven't seen in any of the young wizards other than Harry.
You're right. Harry does seem a little funky in this one, hunh? I think it's about time he gets upset. This whole Harry vs. Voldemort thing is a little much for a 15-year-old kid. I think, by this time, if I were Harry I would want to just live life as an adolescent and not be burdened by knowing someone wants ME DEAD. I might be a little angry too and, really, who do we lash out at most when we're angry? The people closest to us, ofcourse. Harry's attitude will be a true test for his close friends, though. Regarding his being a little upset over Ron's honor: maybe Rowlings is trying to show that he's not above feelings of jealousy? He's got a lot on his plate.
Kingsley Shacklebolt does seem like he will be an interesting character. I would rather see this character played by someone other than Michael Clarke Duncan, though. Since Wizards are known for their intelligence, not their physical strength, maybe someone like Don Cheedle would better fit the role?
The Ministry IS DEFINITELY SINISTER and the new Dark Arts teacher is just awful. I'm sure she will go the way of all the others. I personally think Cornelius Fudge is a Death Eater; he's got all the signs. Calling Harry and Dumbledore loony is just a cover-up. He doesn't want everyone to know that Voldemort is back, so he's discrediting sources that say he is.
That's it for now. I'll come back later.
OH, on a side-note. I went to a birthday party with my chil'ren on Sunday and there was a girl there who saw the book in my hand and struck up a conversation. I was delighted to have someone to discuss it with so I asked her how far she was. Well, she said she didn't have the book yet. So, I asked her how she liked the others. She said she hadn't gotten through them all. So, I asked her how far she had gotten and how she was enjoying it. She said she actually had not read any of the books but had seen both movies, but, she was definitely going to buy the set of 5 soon.

I could not hold my tongue (and I am a very polite person, normally), I just had to say it: "Why don't you start by buying the first one and READING IT." She looked at me as if she wasn't sure what I had just said and I was so surprised at myself that I clamped my mouth shut and forbade myself to speak another word. Eventually, I got up and walked away. I'm an English teacher and a reader. I do not buy books as "collector's items." It is just totally against my nature.