I wish Goodreads did half-stars. Anyway, 4.5 stars. The writing here is really top-notch, and the science that I was able to follow seemed spot-on. I had to take off a little though because while occasionally funny, I found Mark Watney to be pretty insufferable at times. I understand that he's trying to maintain his sanity, but his personality made for a pretty grating read in spots. Wisely, Andy Weir brought in some other characters to shake things up, which I appreciated. He's a very talented writer. I look forward to reading more of his work. Highly recommended.