If you have the means to "waste" money on the price of the book, I'd recommend it. But by "waste", I mean that the book could have been a thick pamphlet, but publishers sell books and not pamphlets, so by golly that essay is going to get the shit fluffed out of it until it is book-length. So you're paying for a lot of marshmallow cream.

That said, the premise is good and you might glean some good practices that you'll put to use. It's just that it's not worth the $15, IMO. If you have disposable income, buy it. Otherwise, just go read the New Yorker article referenced elsewhere in this thread.