This book is fantastic. For the price you pay, you get an unbelievable amount of quality, usable examples that are applicable to any business.
I used the handwritten sales letter example to try it out. I sent out 20 letters and within a few days had two new customers making this my best return on investment from a letter this year. And that's after just 20 letters sent out! I'm already getting ready to send it to more customers.
I would recommend this book to anyone. You can't lose. At worst, if you apply a strategy from this book you'll make the price of the book back within days, multiple times over.
I would rate this book as essential reading for anybody that's serious about growing their business.