This show was amazing. It's my new favorite KDrama. I never realized a KDrama could be this good. It truly is something special.
The story certainly isn't perfect. There are some odd leaps in logic and some twists that are a bit too wild, but the vast majority of the story is well crafted and incredibly well written. I am stunned that the writer was actually able to pull off two connected stories going simultaneously without anything too weird happening. I have no words for how impressed I am. There are some plot holes left at the end, but they're small. I feel like any loose ends are actually hinting at a second season, but if there isn't one, it ended nicely enough that it's okay.
The acting in this show was fantastic. Every actor hit every mark. It was perfect. Yeo Jin Goo has skills beyond his years. Kim Kang Woo had to play a character with many sides, and he did so with such talent and finesse. Gong Seung Yeon is more than just a pretty face. She knows what she's doing. I underestimated Lee Ki Kwang. This show marks one of the few times where an idol totally blew my mind. I expected him to be the worst in the cast, but he was on par with rest of them. He was great. The extended cast and younger versions of characters were fantastic, too. This is an unbelievably solid cast.
The music suited the show, and there was more than one song that I really liked. Uji's OST was especially good.
I would definitely rewatch this, now that I know everything that's going on. I feel like seeing it again would allow me to catch hints that I missed before.
I really loved this drama. It's not perfect, but it's so close, that I can't help but give it a 10. I definitely recommend it.