The show uses a lot of borrowed fantasy elements (both literally and figuratively) from other K dramas and western shows, which will make it feel less original and familiar. The show is an adaptation of YLAB's webtoon, "The Island", so expect a comic book feel to the story and action sequences. Special effects and scenes will also seem familiar with another show produced by Studio Dragon called Alchemy of Souls.
Van, the lead male character, is an ancient demon slayer. Van's origin story reminds me of The Witcher in some ways. But he is a serial killer in the webtoon, so I'm not sure if they will work that into or out of the TV screenplay. (Trivia: Korean spoken language has no "V" sound, so why "Van", I don't know.)
As a horror genre show, it's decent enough to watch. Live-action adaptation of comic book/anime/cartoon shows are challenging, but this show should to be entertaining enough for those not familiar with the webtoon.