Quick-take: This book is a gift to fans of problem solvers.
Through pure grit and ingenuity, Mark Watney will fit any square peg in to any round hole he finds and survive being left behind on Mars. After this novel, Macgyver will be calling Watney for problem solving tips.
What is truly impressive is each and every screw-up and duct-taped solution seems to "work" and Mark's band-aid on top of band-aid style of problem solving and absolute resoluteness of refusing to die. He throws something together and explains the science behind and I just think, "yeah... I think that could work." I mean, I am not going to lab-test it personally, and this book is fiction, but it all does sound very plausible and intensely researched. This repeated problem->solution approach as he gradually inches his way off Mars is very engaging.
I saw the Matt Damon movie before going in to the book. The movie follows the book quite closely and in some ways is even better. While I appreciated the deep-dive on every solution Mark threw together, I didn't quite need all the minor details (running tallies of oxygen levels, solar panels, and batteries, etc). The movie takes a higher level view.
While the book is great and deserves 5/5 stars, it was already spoiled for me from having seen the movie. If you have not seen the movie, then of course read this book. If you have seen the movie, I wouldn't bother unless you just want to relive it on a deeper level.