Like many, I bought this book after people recommended it as a good book for learning about polyamory. It's been sitting in my garage since that first painful read through. I learned more from website FAQs and friends than I ever did from this book.
If what you're interested in is swinging, or a poly relationship where people are regularly finding casual partners, this book may well be very useful for you, and don't let me put you off buying it if that's what you're looking for.
If you're looking for a book that will give you information and guidance on closed or more family based, or long term poly, this book is not it. You will get this book recommended to you regardless of what your situation is anyway. My girlfriend and her partners are generally in a semi-closed situation, and this book couldn't be less applicable for us.
My recommendation would be to start with Xeromag's Poly FAQ and go from there.