I have recently finished reading "The 4-Hour Workweek". Timothy Ferriss did a good job of writing a book with a catchy name that's quite interesting to read. It's an interesting book but I would not say it's great.
If you have ever read some newer texts about time management or about using e-mail efficiently (e.g. this manifesto), you will recognize some of the ideas that appear in the book. What the author does is that he takes those ideas to an extreme. Maybe the aim is to provoke people to really ponder what they do and how.
The chapter on setting up a low-maintenance businesses is U.S.-specific but still quite interesting, especially the part about testing market response. The weak point as I see it is product selection: the suitable products should be easy and cheap to produce but must be salable at premium prices. That's sets aside anything more complex or with a higher added value.
Overall, the book is worth a (critical) read but you do not need to put it at the top of your reading list.