Pretty much read this as fast as I could, I was hooked the entire time! 

It follows the same formula as the Martian, and adds a twist (a new character), so there are two leads that play off of each other.

I hope the Eridians and Earthlings make peaceful contact one day 🥹

The best story is the first one (Priest's). I also liked the Brawne Lamia's story.

The book's plot is incomplete without the sequel, so make of that what you will. I thought many of the character stories were much more long winded and dragged out than they needed to be. 

I watched the movie first, and then read the book in quick succession. Overall, it was an engaging read. Despite the dire circumstances, Mark Watney's sense of humor carries the book pretty far. Also, even though it was science fiction, it pretty much read like a nonfiction survival story. 

Spoilers: 

I'm surprised the movie cut out the actual journey to the MAV at Ares 4 and the dust storm, it was the most tense part of the book. Also I liked how the book ended with Beck dragging his body in and taking him straight to the medbay.