Andy Weir's The Martian is about a man who gets trapped on Mars. It's about all of the actually plausible-sounding science he uses to get himself out of one scrape after another. It's about the efforts of people back on Earth to get him home. It's about (we suppose) triumph in the face of adversity, and the innate goodness of humanity.
In this case, what hurts the book the most is what it isn't: it isn't a particularly interesting character study, since the wisecracking astronaut Mark Watney seems to sail over every obstacle the red planet throws at him without much physical or psychological damage. It isn't a treatise on solitude (Watney rarely seems particularly affected by his loneliness in any lasting way) or on the darker side of human nature (there are no adversaries aside from Mars itself). What's here is a breezy read that's got some entertainment value, but it doesn't have quite the impact it could have had, which is a shame.