Officially becomes my best drama of all time. It was so good and I feel like I was on a journey. Two months I have been with this drama, waiting everyday for a new episode but today I can't do that anymore. Hoping for next season even though I know it won't happen.

Story
A sci fi, fantasy, romance, and thriller drama. It is a roller-coaster mood. The tempo of the drama is fast. The story also has a lot of plot twists. And I love it. What makes this drama even better is that it almost doesn't have any particular plot-holes. The romance story was attached to it, and most people will agree that it is part of the story.

Acting/Cast
Seo Kang Joon arguably has the hardest roles in K-drama ever. Not only he acted as Human and Robot, he also needed to act as robot pretending to be a human, human pretending to be himself, human pretending to be a robot, which are really hard. He has done a fantastic job. Hats off for him!

Gong Seung Yeon on the other hand, played as Kang So Bong. She also did a great job. Her acting to show Kang So Bong's reaction and emotion is totally amazing. I'm becoming her fan. Her part is also hard. She needs to build chemistry and also she also needs to build hatred feeling to the same person. Everytimes she cried, I also cried. I feel like I'm in love in her and Kang So Bong.

Other casts were doing a great job as well.

The dynamics of relationship between Nam Shin 3 and Kang So Bong is also the best. Kang So Bong has the most complex emotion, followed by Nam Shin (people will argue that it is otherwise, I would still stand on my opinion). Kang So Bong had felt hate, disgust, pity, joy, sadness, anger, and love to Nam Shin 3. I love their romance scenes.

Music
The music were great, but their osts wouldn't beat the likes of Goblin and WYWS. Some of them were misplaced. But they are still good as standalones.

Rewatch Values
I would love to rewatch it again and again and again. I hope there will be a second season. Painfully it won't happen