This drama was just a beautiful subversion of the genre. It consistently did things differently than how it would play out in other dramas that cover mystery/thriller.

The strongest point of this drama is how cohesive it is. Multiple aspects of the production are linked together through details in the same way the main characters have a link. It's a sign of their hard work and thoughtfulness. Things like similar style clothes, matching camera angles for the two leads, and symmetrical backgrounds make for great visual representation of the concept.

As I said in the beginning, this drama subverts its genre. So it's not for everyone. It's for people that want to watch a different type of mystery/thriller romance.