Tim Ferriss does a lot of things right in his first serious foray into the writing world. He crammed his book full of very useful life-hacking tips, including actual websites where these ideas could be followed up on. He included tons of interesting tidbits about his life and how he has seen angles that others haven't been able to. And perhaps most importantly, he emphasizes that each of us can be just as successful if we put our mind to it and maintain the right attitude. This book doesn't lack details, which separates it from many of the other self-help books I have read and is probably one of the key reasons that it has been so high-grossing.
Nevertheless, his book wasn't flawless. One of the main gripes I had with Ferriss's style was his attitude that the world should be working for you. He suggests that everything be outsourced, from checking your mail to researching column topics, so that you can pursue the things that you ought to care about. This is a cute idea, but there are two problems it doesn't account for:
a) You can't take an order or check a pulse while you're halfway around the world. Doing your business mobile works for some industries, but certainly not all of them.
b) It totally disregards the notion that your occupation is at least partially about doing some good in the world. If you want to be an activist, Ferriss encourages you to streamline your main occupation and commit yourself to volunteering. But what about organizations that provide valuable services or perform research critical to solving novel diseases? Maybe I'm young and idealistic, but I think that some professions might be worth not quitting.
Ferriss writes funny, quick, and interesting. You have to respect the way he has reinvented his own life. But keep in mind that while forging your own path in life is admirable, the way he specifically did it may not be for everybody.