Not bad but there are too many illogical elements... I mean, okay it's sci-fi, but still, some elements are like "hey, we put them because it's cool because it's sci-fi" but don't have a logical sense or even a meaning. Maybe if there's really a second season, some of these elements will be explained, but there, just with these episodes, I feel that the drama is incomplete, really messy and the sci-fi elements without any purpose. That's strange because I'm the first to love this kind of drama/story actually but there are too many messy things, illogical stuff and so on that make me feel like "Huh ? Like, okay ? But, no ?".

Still, the plot could have been really good. But the writing is really not as good as the idea. Maybe if they really make a second season, it will be better/make me feel better about this first season. But just with this season, I can't say that this drama is really good. It's just okay to watch once.
And what made me feel like I was watching an average drama is that the storyline is really obvious and predictable. I mean, I guessed many of the "suspense" elements and of the storyline at the beginning. I don't know if it was luck or if it's because I'm used to this kind of drama, but it was pretty predictable for me. I was waiting for more from this drama.

But still, the acting is pretty good and nice to watch. The OST is good enough too.

I think I'll rewatch it only if they do a second season.

Note : but at the end of the last episode, they say "new leads with new stories", so I don't think that the second season will bring more elements about this first one ? I don't know. But I hope that they will make a second season so it, perhaps, make me feel better about this drama ahah.