"Contrarian" would be a good one-word summary of this book, and one of its strong points.
Rather than joining in the "everyone is an entrepreneur!" hype, the author rightly points out that no: it's difficult, and it's not for everyone, and to really be called an entrepreneur, you probably ought to be able to point to significant value creation.
As the author points out, it's not really about innovation per se: there are plenty of innovators who don't manage to create businesses from it, nor capture much value. And there are plenty of good businesses that don't really innovate a great deal - one of those profiled in the book is a group that created an American style Cinema chain in Mexico. They basically changed nothing about the format besides, of course, the location, and adding some spicy popocorn.
The central thesis of the book is that most people who really do create something new and big are often viewed a bit askance at some point along the way. As per the title, the new business is seen as either worthless, impossible, or plain stupid.
And - many new businesses really are - but the trick is the ability to be an independent thinker, and to persevere in the face of difficulty.
The book doesn't have a lot of actual advice, but I liked it. The tone is, in some cases even a tad "grumpy", which I found a refreshing change from some of the "rah rah!" material out there, and the author takes some shots at various ideas like "intrapreneurs" (as heavily promoted in The Lean Startup): those people are often not really going out on a limb, and neither are they really going to get the huge rewards a "real" startup will. I appreciated the honesty, and also reading someone with a unique point of view: being a programmer, I fall into the orbit of Silicon Valley for some things, and that place can be a big echo chamber in many ways.
I also appreciate some of the policy recommendations: stop trying to pick winners, just make doing business easier for everyone, and what will be, will be. Politicians hate to hear that, because they want to be the protagonists, or at least supporting actors. But the reality is that the economy is too complex, and trying to determine which sector to favor is a losing bet.