Actually it should be a 4.5 star rating. The reason why I love this book is that I totally love the protagonist Mark, he is just humorous and always optimistic. I kept giggling through the entire book because of him. However, I still have two problems about this book. The first problem is that I cannot understand many of the scientific stuff which perhaps is my own fault. Maybe I am just too stupid to understand some of the context. The second problem is the ending, I just want more of it. What happened when Mark returns to earth? Can he live his life after living in Mars for nearly two years? I can only imagine those things, but that is also the charm of reading I think. 
 Overall, this is a great book and I definitely recommend you to read it.