As has already been stated, the true value of a book is the value you get out of it. The books place in popular culture shouldn't raise or diminish your feelings towards the information inside. We're all (hopefully) reading new books constantly, good and bad. The worst you're out is $30 dollars and a week or so of reading time. You can even recoup some of that cost if you blog about it (generating income) and have a used bookstore nearby that you can sell it to
The two most important points in the RDPD book(s) for me have been:
1) To affirm that I want to be in the Business / Investor side of the quadrant, despite massive pressure from the world at large to wedge me into the Employee / Professional side.
2) Assets put money in your pocket, liabilities take it away.
The implications of that asset / liability difference are
huge when you look at how the average person "invests" their money. Even if the rest of the book had been a complete waste (it wasn't) I would have felt I got my money's worth on those two points alone.