This is the book in the series that J.K. Rowling was writing this series in a way that had it grow with us. This is the climax or buildup to the climax of the series arc. It's a definite eye-opener. It allowed us to learn more about the wizarding world outside of Hogwarts. It's a change in pace and should be recognized for setting up all the pieces for the next three in the series.
Ala the meme, this is also the movie where: "Hermione Granger and that time I saved Harry with research, Again. All the time. Really, he would have died without me." Truer words could not be said.