This is probably the most enjoyable of the several different books of essays on the Harry Potter books that I have read. Perhaps it's because the contributors are, themselves, fantasy and sci-fi authors, which may give them a unique insight. Another possibility is that this is also the first collection to cover all of the books through Half-Blood Prince.
As with any compilation of work by several different authors, the quality of the essays is uneven at best. The contributors stretch to come up with original ways to look at the series and, inevitably, they sometimes fail. The ones that fell the flattest, in my view, were "The Proper Wizard's Guide to Good Manners" (Roxanne Longstreet Conrad) and "Harry Potter and the Post-Traumatic Stress Disorder Counselor" (Mercedes Lackey).
At least, however, those two essays were near the end of the book. Throughout my reading, I never changed my view that the first essay, "Harry Potter and the Young Man's Mistake" (Daniel P. Moloney), was the one with the profoundest insight and most thoughtful probing of the pitfalls that Harry faces in his final struggle against Voldemort. Honorable mention also goes to "Harry Potter and the End of Religion" (Marguerite Krause) and "It's All About God" (Elisabeth DeVos), which should be mutually exclusive but, surprisingly, don't seem to be; "Hermione Granger and the Charge of Sexism" (Sarah Zettel), which should (but won't) dispose of that one once and for all; and "Why Killing Harry is the Worst Outcome for Voldemort" (Richard Garfinkle). All in all, a very enjoyable and satisfying read.