Initial warning: I'm a science nerd. Not that I'm good at science, but I really enjoy reading about science: Tell me how to split an atom and I get a boner; show me a path around the space with two slingshots effect and I jizz in my pants.
That's why I liked this book this much. It is kinda like the movie "The Core", but without the bullshit plot and materials and whatnot.
So it seemed, at first, that the book was only about one guy lost in Mars and his attempts to survive. But the book encompasses a lot more than that. Without giving too much spoilers here, it explores a bit of science, how the space companies work, how much work it takes to launch a single rocket and so on.
As I mentioned, there is a lot of science in the book: How create water, how to create hydrogen, chemical reactions...
In the end, it is a really good book if you're a nerd.