In my honest opinion, the drama started very well with a nice storyline and seriousness that piqued viewers engagement, but i felt the writer lost the plot and wasted a lot of episode focusing on things that didn't really matter, instead of actualizing Kang ho's revenge.
Additionally, i felt that the writer could have done a better job instilling a level of seriousness, rather than turning it into a comedy as that didn't play out well.