I really liked the plot, which I feel sent a very meaningful message to viewers, and caused me to become reflective as well. The main reason why I thought this drama was good is because of its message and story that it tells. Though some felt that Cha Eunwoo's acting was bad, I personally feel that he was just portraying his character's stoic and rigid personality, and it is not that he is unable to express emotions. Kang Mi Rae grew on me as well, even though I did not particularly like her at the start, the actress did a good job at portraying her character as well, and it allowed me to become understanding of her character. I also think that the other actors did good jobs as well.
TLDR, I'd recommend this drama mainly because the plot is meaningful, but also because the acting is good.