The underlying story, so far, is one of the stronger ones. And this book does have a worthy villain in its new Defense Against the Dark Arts teacher.
The two things I find myself wishing are:
That the book was much, much more concise. Given the amount of story that’s actually taken place so far, I have trouble figuring out just why 600+ pages were required to tell it. Perhaps it’s a matter of wanting more story, fewer details.
And, more: that just one of these books would be plotted in such a way that the plot doesn’t rely on people failing to talk to each other. This is the point that makes me want to scream–because there are ways to plot stories without requiring the characters find bad excuses not to speak to each other, really there are. Not even very hard ways, at that.