It's so good. It's just so good. Even though I already knew the story because I've watched the movie several times, there was SO much more information in the book, more science, more events, and even some key differences that made it better (although the movie is still very good). I had no idea how much I like this technical style sci-fi until I read Project Hail Mary over the summer, and now I hope Andy Weir writes a LOT more books.