Spoilers obviously
The show was incredibly violent to the point that I felt sick a couple of times watching it, particularly with the organ harvesting, but I also have a very weak stomach. The marbles episode was brutal to watch, and I was somewhat invested in the character stories, which doesn't happen too often when I watch TV anymore. I thought the sleeper antagonist of Sang Woo was great. The twist of the old man being the host was great, but the final scene was kind of lame. I mean, he is going to take on the illuminati by himself? He should have just got on the plane and reflected on all the events. But I get you have to leave your stories somewhat open ended to allow for more seasons if possible.
Definitely worth watching as a thriller. Would recommend, make sure you watch with English subtitles and not the dubbing, or you won't be able to appreciate the great performances, particularly HoYeong Jung and Park Hae Soo.
Also GO COUGS