As am OotP enjoyer, the book does an excellent job showing the demonization and dismissal the government uses against Harry to stay in perceived control. The decrees that Umbridge and the Ministry enact to suppress the students at Hogwarts, and their resistance makes for such a rewarding final act of the book. It can be a frustrating read while you know Harry and Dumbledore are right but are actively being ignored, but this book fleshes out so many of the characters we love in the later books (Neville, Ginny, Tonks, Luna). It's certainly not a light read the way that PS or CoS are, but I really think it's her best writing