I came to this drama post CLOY, in search of more Hyun Bin. Well, nothing beats CLOY, of course, but I thought the storyline here was a fascinating premise, and HB did a great job with his two selves, especially towards the end. Episode 19 is a heartbreaker. Unlike other reviewers, I did not feel the story was out of balance or that one character was more likeable than the other. They were two parts of one man. And when those parts begin to merge, we witness the pain and surprise for each character.
The FL here is wise about the heart, memory and human behavior. I appreciated the fact that she is often the emotionally smartest one in the room and is given the most perceptive lines. Of course it would have been nice if she had a life that was depicted outside of these two men. Unfortunately, her main job is to be the foil.
The two things that made this hard to watch are the two villains. Both are so over the top. I really wish the writer and director had taken it down a notch or two with these guys. Evil capital E is exhausting. I hated when they were on screen (and sometimes skipped through those parts). Too much of their storylines is unbelievable. The scenes with the hypnotist-therapist were especially a slog.
As a total experience, this drama is dragged down by the two villains and the slow pacing of the middle episodes, which all undermine the curious intelligence of the premise. HB is best towards the end, when his acting is more nuanced.