I'm sure some think it's phony balony and get-rich-quick stuff, but a quick Google search reveals many people worldwide who have actually put it into practice that are enjoying the benefits of this new attitude towards work.
I've tried various techniques discussed in the book at many times during the past 20 years since I graduated college. I've been self-employed as an investment adviser, insurance agent, janitorial business owner and I've worked as a car salesman, restaurant manager, pizza delivery guy, and financial analyst, and a supervisor for one of the leading captive finance companies in the world.
The techniques in Ferriss' book are like most theories....those that actually attempt to implement the suggestions are often rewarded with the benefits.
I think it's a mistake to dismiss this book as a gimmick or hype. There's a lot in the book that rings true. Most people would do well to read it and implement some of the ideas that make sense according to their individual circumstances. Like an all you can eat buffet, pick and choose what you like, and leave the rest for someone else to enjoy.
Example: Reduce the amount of time you spend working on the weekends and spend it with family and friends instead. How? Use some of Ferriss' tips and suggestions to get more work done Monday through Friday.