If the intent of a "how-to" book is to give one some instruction before attempting their career in earnest, then I am doing it all wrong, since I've been writing for years (some of those works being mysteries) and having some success, albeit limited and nowhere near the level of the author of this book, James Frey.
This James Frey shouldn't be confused with the discredited/disgraced author of the sham memoir "A Million Little Pieces" that Oprah flogged pretty hard to her Praetorian Army of housewives in her Book Club, as this guy (James M. Frey) is a good writer and explicitly writes fiction (when not rattling off the How-To books).
So no, I didn't read the book to learn my chops or build some kind of foundation, but more as a way to bone up on some familiar ideas, strategies, tropes, concepts, and techniques dealing with how to write a mystery that avoids cliches, keeps the reader engaged, and (most importantly from Mr. Frey's perspective) catches the eye of an agent and allows one to get their creditors off their backs.
Depending on your own philosophy, Frey either comes off as unpretentious and practical, or a bit of a mercenary who doesn't so much follow his muse as she soars, but hobbles her (a la Misery Chastain) just to keep her from running riot and leading him toward a goal that's too lofty or esoteric to help him pay the rent. I like both "literary" or "high" fiction and stuff that's considered low brow, so while I was not totally in accord with Frey, neither did my monocle drop into my fizzing chardonnay when he talked like this.
All in all, there is a lot of good, concrete advice about the general mechanics of the writing process, and various stylistic pitfalls to avoid. The more specific advice about the mystery genre itself wasn't revelatory or new for the most part, and Frey doesn't try to pretend it's native to him, but sometimes even the most seasoned expert needs a refresher on the basics. And it goes without saying that if you're just getting started in the game, Frey's book poses no threat of steering you wrong and may actually help you along your path. Good luck to you, and to him. Recommended.