Harry Potter and the Order of the Phoenix (Harry Potter #5) by J.K. Rowling
There are going to be spoilers in the post above this. I'm going to leave a blank space on both ends, so you shouldn't be able to see spoilers by accident while you're reading this one, but I thought I still ought to leave a warning here, so you'll be careful. Oh, and some might consider this post to have spoilers, but I tried to be suitably vague about the stuff that isn't super obvious right away. So whether you should read or not depends on how much you hate any hint at all of the contents of a book.
I'm afraid that I disagree with you and Tracy even more on reading this a second time, Andrea. Sorry. I had remembered this as a book that I liked in spite of all Harry's whining, which I thought wasn't too bad considering what he's been through and all that. Now, reading it again, I wonder, what whining? I mean there is some, but it didn't seem to me that it drags on particularly or anything. I thought what there was seemed entirely consistent with, well, everything. I thought the characters were consistent, all the reactions made sense. Melanie, I remember you were upset he never apologized, but, again, it seemed like he and his friends acted as they always have. There were times when he did say sorry, and there were times when they made up nonverbally, as friends do. Even Dumbledore seemed consistent. If he had explained his actions as intended to protect himself, that would be one thing. But he didn't. It was for Harry's sake, he didn't want to tempt Voldemort. So, what with all the consistency, you can see why I don't feel that there's anything at all about this to make it "fan fiction" or "not canon."
Umbridge makes a really good villain. Almost too good, since she makes the book harder to read. I mean, Voldemort is evil and all, but at least he's honest about it! Umbridge, on the other hand, made me sick. Not to mention enraged.