So I saw many bad reviews, but I waited for this drama for so so long, so I went with a clear mindset, and to be honest, I enjoyed it.
It's not as great as I thought it will be, looking at the cast, plot, and all. But it was okay. I think it's more of an opening to a story, than, a drama itself. The music was amazing, the cinematography was nice to look at, the acting wasn't bad, not the best, but I have nothing to complain about. The fights reminded me more of anime ones, they look interesting. I didn't like the characterization of the demons, it looked so fake, they weren't scary, just funny.
But I still give it an 8 because I know there will be season 2, so as for the introduction I enjoyed it.
Don't look at the bad revies and just go watch it, and check for yourself.