I'll spend little time discussing the themes of law enforcement in this book; others have done so better than I as a white person could ever do. Keep those reviews in mind before anything else: what I want to focus on is the excellent use of foreshadowing throughout the book. Spoilers ahead!
From the very start, payoffs are set up that won't come back until much, much later in the AP. Here's a mysterious zoo attack; the perpetrator will come back later. Here's an NPC that'll show up in the final book and help! Here's more who you'll meet later; some obviously antagonistic, some seemingly innocent. Setup for future books which could have completely been omitted as in many other AP volumes makes this a book with a narrative that'll weave in on itself throughout the adventure path. I can't wait for the glint of recognition in my players eyes followed by shock and surprise later on when mystery elements foreshadowed as early as the FIRST ENCOUNTER come back months later. And the fact that the book tells the GM that this will be important later lets them hype and build the scene with the due respect good foreshadowing needs without even having read the next books yet.
Whatever your take on the themes of Edgewatch, Paizo take note: this is how you set yourself apart from other APs!