One of the important considerations for any story, in any medium, is keeping the audience engaged. One of the important components of this is the plot having a driver.
Now, I don’t mean like a recent film about a chap with a natty scorpion jacket; I mean there must be something (or someone) that is pushing the plot onwards.
My concern with Order of the Phoenix is that it lacks this driver (at least in the stuff-happening-at-school section. Harry is largely a reactive character – which is fine, often the antagonist drives the plot by trying to achieve World Domination(TM) – but he’s not being given a challenge to react to at the moment.
No, that’s not true. He is, and in the form of one of the most easily-hateable villains in the whole series: Dolores Umbridge, the sadistic, twee figurehead of the Ministry of Magic’s attempts to take control of the education system*.
The trouble is, this feels somewhat artificial, and not really related to the main plot of the series (Harry vs. Voldemort). Sure, Harry reacts (when pushed) by starting Dumbledore’s Army, which goes some way to ensuring Umbridge’s poor teaching doesn’t hamper the students, but it does nothing to resolve the apparent larger question (i.e. how to get political noses out of the Hogwarts’ business). Harry is advised to keep his head down, and… And what? None of the staff, not even Dumbledore, seem to be doing anything to get rid of Umbridge beyond enduring and hoping she’ll give up eventually.
Now, granted, the whole concern is because the Ministry doesn’t (want to) believe that Voldemort has returned, and the interference is more to keep Harry and Dumbledore quiet. In that sense, Dumbledore is working to resolve it by convincing the Ministry of the truth, but as he’s also avoiding Harry for most of the book, we don’t really know what’s going on.
The kids are on their own, and they’re not really sure what they should be doing. And in typical teenage fashion, their reactions are focused on the short-term issue (passing their O.W.L. exams) and not on the big picture.
Oh, and Voldemort’s busy sending Harry mysterious dreams about a door in the basement of the Ministry, but that’s not at all important to the overall plot. Foreshadowing ought to be subtle, but it still needs to “stick” to do its job. I’ve been surprised at how often dreams are mentioned in the early part of the book; repetition alone does not ensure recall.
* Incidentally, I believe the author worked as a teacher for quite a while. It doesn’t show. Much.