This book was a pivotal tool in my quest to retire early. It encapsulated and confirmed everything I'd learned from my own research, and served as a guide and reference. It's packed with a ton of vital details. It provides an excellent investment strategy and model portfolio, tailored specifically for early retirement; it discusses taxes and how to minimize them; it talks about the withdrawal rate, and provides plenty of charts and tables to show how different withdrawal rates hold up for various time periods.
It also has quite a bit of fluff, but it has a nice way of sparking fantasies about how nice early retirement will be. It talks in great length about the psychological struggles of being retired, which may be an even bigger risk than a stock market tumble. Still, I think a lot of this fluff could have been trimmed, which would have turned this into one powerful little book.
This book tries very hard, probably way too hard, to portray early retirement as a vast grey area, rather than an all-or-nothing proposition. It almost always calls it "early semi-retirement." In nearly all examples, it includes the option to subsidize retirement with little side jobs. I think this is great, because it makes the whole endeavor far more realistic and achievable, but I also think he took it too far. Sadly, I think most people walk away from this book remembering that it's about how to settle for a partial retirement, rather than its real strength, which is the investment, withdrawal, and tax advice.