Andy Weir created a powerful and very enjoyable main character. Man, Mark Watney is really fucked up! Because he is alone. On Mars. Without enough food and water. Impossible to survive that!
BUT he's a botanist (!) and a very intelligent engineer (let's just say he's MacGyver reborn on Mars) and he says the words "I'm fucked up" very seldomly. Just fear his botanist powers!
And he ist very cool. His glass of water is always half full. He never gives up. And he can be very funny and has a sense of humor I very much liked.
He and his dealing with the situation made this book very enjoyable.
So why is that full fifth star missing?
This book is very well researched. Really, while reading this I thought: Man, that sounds like a thing that could really happen! Physics, Maths, Botany - all on board and all of what I expect while reading a great Science-Fiction novel. But the technically descriptions of Watney's 'repairs', 'tweakings' or whatever were sometimes a little bit overdone / extra detailed (sorry for that, I'm no engineer and lost contact sometimes and I admit I overread some of it ^^)
Nevertheless a great read. SCIENCE. And suspenseful. With a great main character. On Mars. :-)