I was looking forward to this, Jung Hae-in being one of my favourite actors.
I just read the main storyline before and thought it sounded promising, but the actual series didn't deliver it for me.

The start is just confusing. So we are where? In a dystopic parallel world? Or in our world? I don't know, because if someone like the main character really existed with these kind of healing and recovery powers, and that would have been known since his childhood, he would not have seen the light of day ever again because every nation in the world would have tried to put him into a laboratory and disect him to find out his secret. That at least was my first thought after 20 minutes in.

The next thought was, who are all these people, why do all the things happen, and at some point I felt annoyed as the main character loudly speaks all of his obvious thoughts in a way nobody really does. It's just something I don't like in general. I don't like being spoonfed every single thing like that. For all the abilities he possese he seems awkwardly helpless and clumsy most of the time. I finished the first episode and most of the time you see him clutching his missing eyesocket or both his eyes in panic and uttering obvious things. He is steadily on the run and can escape, until a very tiny woman shows up, (either knowing all the secrets for an unknown reason or just trying to be the weird 'I like creepy things'- character) and after seeing his healing ability, happily throws him off a roof. Oo

I honestly didn't like any of this. It's dark, and I like dark, but this just feels unpleasant. The characters seem flat and constructed altogether, and I don't like any of them, at all, it just seems sterile and weird to me. It also reminds me of rather bad copies of some Marvel movies I didn't finish either because I disliked them.
You get thrown into the storyline without any necessary background information, instead there is lots of graphic organ cutting, pulling and slicing and this steady rather helpless out loud commenting of the main character. It would have been so much better and more intelligent the other way around. Give visual background, let the audience think and let it understand the mysterious lead character by his actions, his gaze, etc.

I stopped watching after the first episode, so if it got any better or even brilliant later I might have missed that. I simply didn't care about any of the characters or the story, it just seemed too artificially fabricated and thrown together in the attempt to create atmosphere and tension - which sadly it failed to do.