I read the prequel to this book and I enjoyed it, but I am pleasantly surprised to find that upon finishing Aftermath that I liked this book more. Strangely there is something refreshing about this title; it's not all bad, doom and gloom, end-of-the-world stuff, but rather a "if it happens we will deal with it and move on" sort of book. Nonetheless, the basic premise, more than anything, is that governments of the world should get prepared to "deal with it" sooner rather than later--whatever "it" may be.
Some of the biggest threats that our planet faces and for which we are ill-prepared for are comets and solar flares frying the power grid, both of which would send civilization back to the stone age. Joseph posits some great points about spending more on preparation and defense for these sorts of scenarios, rather than on the usual war budget, global warming FUD (for both the proponents and opponents) and fear-mongering that is typical in public discourse today.
The last couple chapters are sort of "meh," circuitous and repetitive and reminiscent of something written with a certain word count/page count needing to be achieved to be finished. I won't call it "filler," there is stuff to be learned, but the most important and interesting stuff takes place in the first two-thirds of Aftermath. For this reason I have not given it five stars.