I'm surprised with this drama. Originally I wanted to drop it after the first 2-3 episodes, I ended up binge watching it in one day. I recommend anyone watching to at least watch to episode 6 because for me that was the breakout episode where the show really shined despite all it's fault and I'm upset it only had 14 episodes.

Story: The writing was a mess to put it simply. Yet, the acting and stand out scenes really do save the drama from it's own story. FL at first was annoying and bothersome with how impulsive she could be. Eventually I warmed up to her, I wish she could have gotten more development.
If your looking for an amazing mystery story, this is not at all that. The psychological element of this drama is the best part and the romance is pretty good too, just there's not a ton of romance.
The biggest crime of this drama would be the last 2 episodes being cut, because I think those would have made the plot more well rounded and probably added more scenes between the ML and FL which would have been nice.

Acting/Cast: All the actors for this drama were really good. But, Jang Hyuk's performance was by far the best and is enough reason alone to give this drama a chance.

Music: Not much to say, it has a very small soundtrack with the main theme being outstanding.

I'd say give this drama a chance, it's lack of a cohesive plot is entirely made up for with the acting and music and chemistry between the leads.
Sometimes this drama isn't fantastic, but when it is holy crap is it good.