I got the same book. NO!! you do not have to pay for it or send it back!!

It is a violation of the Federal Trade Commission Act to send unordered merchandise through the mail unless it is a free sample marked as such or is sent by a charitable organization asking for, but not requiring, a contribution. Most states treat unordered merchandise as a gift. Persons sending unordered merchandise through the mail are prohibited from demanding payment, and you have the right to keep the goods or to dispose of the goods in any manner you wish. Moreover, billing for unordered merchandise may constitute mail fraud and/or misrepresentation.

They are even required to provide you with return postage! And you're right, it wasn't very informative. If you read your Bassmasters Magazine, then you've already read this book :(