I did read it a while ago. His take on investments was interesting, I believe he broke them down into 3 types: primary, secondary, tertiary. A primary asset would be land for example. A secondary asset would be a house on the land. A tertiary asset would be a paper claim to a secondary or primary asset, so to continue this analogy, shares in a REIT. His basic thesis was that every one in tertiary assets is screwed. Only those whose wealth is tied up in primary assets, and possibly secondary assets will avoid being wiped out. This is definitely counter to whats talked about here with index funds etc. Index funds would be in the tertiary category.
He seems to be a very educated doomsday prepper. His arguments are well thought out it seems. I don't have the knowledge to refute any of them, or say hes right.
They did have a follow up book called Prosper! which was basically: yes the situation is dire, gute here is what you can personally do about it. I liked prosper much better because it talks about some solutions. The book talks about building a web of 8 different types of capital: financial, social, spiritual, physical, etc. You may not be in a position to acquire primary or secondary assets (financial capital), but you could build up some of the other types of capital. These other types could help in the types of events he describes in crash course.