In their logs, do NASA astronauts routinely explain minute details about things that would be routine to them? I've never read a NASA astronaut's log, so I don't know. I have, however, read many, many novels, and I do believe it's customary to gussy up one's research rather than just regurgitating facts for a few hundred pages. Mark Watney is set up like 21st-century Robinson Crusoe, but his log lacks essentially all talk of faith and personal evolution that Defoe included in his novel. Watney's got a lot of time to think, and I'm not sure I believe that he would devote all of that time to problem solving and 70's sitcoms. In my experience, even science nerds (and sometimes especially science nerds) ponder deep issues, but perhaps I'm underestimating the spiritual significance and transformative power of the relationship between Jack Tripper and his roommates. 
 Structure-wise, it seems jarring when about three-fourths of the way through the novel Weir drops into an omniscient viewpoint in the crater. What was the point of that? I mean, he has Watney tell us all kinds of tiny details in his log. An explanation of his situation would seem actually to have belonged there, and yet Weir takes this bit of storytelling out of Watney's voice. It's unnecessary and inconsistent with the structure of the rest of the novel. 
 This book worked okay as a diversion while I sat on the beach testing the effectiveness of my sunscreen, but when I got to the (very truncated) ending, I felt like perhaps I'd not made the best use of my time.