This is a good drama made worse by inserting too many cliche kdrama tropes.

big problems in story progression (characters, especially evil/expendable characters keep making insane choices to escalate things and keep the story going), and standard characterization flaws (villains keep doing unreasonable things, side characters are one dimensional; only used as a lever progress the story and then forgotten/kept in limbo the rest of the time.

I think Yoon Se Jun and Do Hye Ji (eldest son and wife) were among the more interesting characters in this drama. They had their own goals, and pursued them seemingly relentlessly but without being "too evil". They were a unit, always supporting each other, and I was interested to see more of them but in the end they are left alone just be used as comic relief and not much else. This my be one of my biggest disappointment with this drama.