My Opinion:- 4.5/5
Though I am late by more than a year to watch this, but it's never too late to watch an amazing piece of this level.
The cast was correctly chosen, Kim Seo-Hyung as Detective Cha Young Jin, doesn't at all care about her age and is doing fantastic and hopefully she can continue her brilliance like ever before. (Please give her less serious roles now, enough of stereotyping her).
Ko Eun Ho was amazing.

And Especially Baek Sang Ho, (Park Joon), was an extraordinary villain in his case. Totally fearless and dangerous, egotistical, narcissistic. Wow, like sometimes he literally made me want to tear him off, and that's why he succeeded perfectly as a villain, posing like a God.
Rest that gospel, resurrection, I feel sometimes it was overdid and overhyped at some points. And 16 episodes could be easily fitted into 10 or something. So it's okay. But Its easily rewatchable.