Like everyone else, I think it could have been done better too. The central plot has a lot of potential, because there's something so very unsettling about religious horror. It's just that most of the storylines were half-baked, including the main one, and had they given it atleast two more episodes, they could've done justice to the story.

I really had a problem with the lack of lore exploration. I would like to bring about some comparison with the movie 'Svaha'. Svaha also had a similar Buddhist outline, and did pretty well in terms of lore exploration, enough to have us creeped out, but ultimately failed when executing its final act to combat the supposed root of evil. Monstrous on the other hand executed its final act to combat the spirit well, but it was unsatisfactory because, other than the fact that the Buddha statue was haunted, we were provided with little to no information on the 'whys' and 'hows' of the statue: Why did a holy statue built under the jurisdiction of a Buddhist temple get possessed? How strong was this measly con-man, so much so that he could possess a BUDDHA statue, and require a super powerful monk's help to seal it's energy? Was something inherently wrong with the statue beforehand? Who lived to tell this tale so that Ki-Hoon could identify the rain as Monstrous rain? How did Ki-Hoon know about the mysterious protection symbol? I'm sure no ordinary Buddhist historian could just whip that out of their text books. I could go on, and could definitely say the same for the other storylines, especially with regards to the crazy gangster man, the crime that put him in jail, and how he came to be so insanely crazy. The relationships between characters other than that of the main leads were also abandoned due to time restraints: the cop and her kid, the kid and the gangster guy and the gangster guy and the cop. AND what on earth happened to the rest of village during the aftermath, considering the fact that more than half of it's population got decimated? So many plotholes. An episode or two to explore these would have made the show deeper and intense, leaving a dreadful feeling behind. Similarly, plotlines that required suspense, like revealing who the spirit may have been, were easily evaded and handed to us on a platter due to TIME RESTRAINTS once again.

To be honest, this lack of lore is what led to the show leaving but a little impression, despite stellar performances by the leads. Since the show heavily leans on Buddhism, which has a rich historical background, there are many precedents or stories in its ancient texts that can serve as a basis for a well-rounded possession storyline. Compare this to Hellbound, in which the events that take place have no precedent or historical background, which justifies the lack of lore and the unfolding of new information gradually over 8 episodes.

However, I was impressed with the bird scene. Put me on the edge of my seat. That scene is what Birdemic should have been, but alas.

I get the direction this show is going in. If my guess is correct, this may be an anthology series (much like the Conjuring movies, with Ed and Lorraine Warren at the helm), with Ki-Hoon and Soo-Jin facing other monstrosities every season. The new one looks like it would touch upon aliens and whatnot.

Nonetheless, I enjoyed the show for what it is. If only it had been fleshed out better.