I'm not a fan of thriller action dramas, so I was skeptical to watch it or not.
I dare say seeing a really high rating on MDL acted like an incentive for me to watch it, and I must say I'm glad I did.
Love Lee joon Gi and Moon chae won. Both are like the stars in the Kdrama world. Their acting was flawless, and so was this drama.

Story:
Technically, it's full of loopholes. But everything happens for a reason and the interpretations are vast. It's one of those dramas where every problem was resolved ( except for a few minor occurrences).
The writers did a marvelous job keeping everything on track.

Acting:
Flawless, with the least amount of cringe. Even the second lead's story was fully covered. It's not one of those dramas where you get angry over silly, absurd, and nonsense characters. Everyone is there for a reason.

Romance/relationships:
As someone who adores romance In kdramas, even though this drama's focus was elsewhere, the romance was depicted so purely and genuinely that deserves thorough applause ( thanks to the acting and story). You will love the leads, albeit their background story is hurtful.

Soundtrack:
It fits perfectly. The background music pieces composed are delicately embedded to match the stories.

Overall, an incredible choice to watch, even if you're not an Action/Thriller fan. You won't be disappointed.