I really enjoyed this book. I am a mechanical engineer, so I loved all the scientific and engineering details and didn't really have trouble following any of that, but I can imagine some people might not enjoy those bits as much as I did. 
 The tone of the book is what makes it a 5 star book for me though. I love the way this book tells the story through the main character Mark Watney's log entries; it feels very personal that way. Watney's sense of humour is one of the things I liked most about this book. 
 "If I make any mistakes, there'll be nothing left but the "Mark Watney Memorial Crater" where the Hab once stood."