I've watched this series twice. Originally when it first aired then again earlier this year. I enjoyed it both times. As is often the case the actors portraying the young versions of the lead characters were better than their adult counterparts. Don't misunderstand, that's not to say the adult actors were bad. Just that the teens did a very good job; especially Nam Ji-hyun's depiction of the female lead. There were times when the story seemed to struggle with how to handle the two antagonists. I suspect that comes from trying to cause the views to sympathize with those characters without agreeing with their motives or actions.
All-in-all, the series was a good watch, the suspense was well planned, and the story was enjoyable.
All-in-all, the series was a good watch, the suspense was well planned, and the story was enjoyable.