Season 1 was good. Then the plot took a weird turn somewhere in season 2. Then in season 3 it becomes catastrophically bad.
The acting by Cheon Seo Jin is awful.
The plot twists become extremely unrealistic. The “good” characters make mistakes that are not plausible. The “bad” characters get away with things in ways that make no sense.
The screenwriting is just getting more amateurish and far-fetched as the episodes unfold. Very disappointing.