The Martian is about an astronaut stranded on Mars. He's about to die because he's stranded on Mars, but thankfully he's a good natured, sarcastic engineer, so he can attempt to survive for a couple more days before his inevitable death.
The book is extremely well written. It's way more action packed than any fantasy novel I've read. Most novels have to go easy on the protagonist every once in a while, but Mars doesn't know how to go easy on someone. As such, it kept me holding my breath the entire time. I managed to go to sleep in between starting the book and finishing it, but that was more a force of will than anything else.
It wasn't very focused on making the reader think about ethics or their place in the universe (EARTH, not Mars). There were a few things -- it might not make sense to spend gazillions of dollars in a vain effort to try to save one person when you could spend much less to fix world hunger or malaria or something -- but they weren't the center of the story.
However, the author did keep the book mostly scientifically accurate, even if it is a bit improbable, so I still felt like I learned something.
I highly encourage everyone to read it!