While the show is reasonably original and well acted, at some point it simply becomes too complex for its own good.
So many villains, motivations, killings, lost memories, red herrings, that by episode 12 watching this show became a chore. In some scenes, actors literally have to give lengthy verbal explanations about what the heck is going on. Some aspects confused me because in some scenes a character would have supernatural abilities and in other scene suddenly not.
It's choke-full of actively unpleasant characters, so it's not like watching it gives much joy anyway.
The two leads are fine, although I'm not a big fan of this Korean obsession with dolling people up. I just can't take it seriously when two perfectly made up and dressed individuals in expensive ballroom shoes are trying to present themselves as hard-boiled detectives.
Having said that, it could be worth a watch.