This one is a real mind bender. Plot-wise this show was consistently excellent. The story was creative, well paced, and expertly balanced its substantive existential concerns with the borderline soapy family drama. I liked how the writers handled the logistics of time travel. Even with the limited screen time afforded to it I was able to buy into into the romance. I read the ending as ambiguous enough to support multiple possible interpretations, which suits the vibe of the show well. The one downside was the acting was a bit patchy at times. Lee Jin Wook was generally good in this but there were also times when he was too stiff and expressionless. Jung Dong Hwan's performance as the villain was fine initially but got so bad in the later episodes of the show it was hard to watch. His constant slack jawed/bug eyed mugging was embarrassing. I can enjoy hammy overwrought acting under the right circumstances but his clownish performance just annoyed me and was out of sync with the rest of the show.