God's Quiz in general was more mystery/thriller/investigation than medical. The main lead, who's a medical examiner, was doing more field detective work and following suspects than the real detectives. I didn't like how they setup the main lead character, he's genius because of a drug experiment in his childhood and this led to all kinds of made up scenarios stemming from his condition across different seasons. Every season, they twisted it in a different way which took away from having a consistent character. It's the eternal problem of any unplanned sequel seasons in a series. Which imposes an impossible task for any multi-seasons writers.
Production: Seasons 1 to 4 were molded under the same OCN early days template, which all shared the same level of underwhelming production value. Soundtracks during season 1 & 2 were super generic stock background noise, only with season 3 they started to include music. Although season 3 was filmed better but had a much worse audio production in general. Season 4 was a noticeable improvement in production but it still wasn't quite there yet. This is all in comparison to regular shows that were released around early 2010s. On the other hand, season 5 brought with it a proper production and other improvements.
Characters: The dynamic and chemistry of the entire group during season 1 was abysmal, overacting from everyone, forced unnatural interactions and none of them clicked. Season 2 somewhat got better in that regard, you can notice that they got more relaxed but still not quite there yet. The ending scene of season 2 while the ML is kissing, his lips were shivering like crazy. It must have been super awkward to the point that they couldn't afford to have another take. Season 3 took a step backward with its changed cast. Detective Bae Tae Shik brought an awful dynamic to the table. Him and main lead didn't click together and created a bad on screen combination. It's probably why the writer didn't write him in for later seasons. The same can be said about other characters associated with Bae Tae Shik. The relationship and attempted romance between ML and Kyung Hee during season 1 & 2 was plain awful to watch. Only in season 4 it got reasonably better and season 5 fixed this issue completely by dropping the childish romantic tension and having them behave like adults. I liked seeing Kim Jae Won as a flashy villain in season 5, it was fun watching a different type of role from him.
Story: The structure of every season consisted of having a few cases then dedicate the last 3 episodes to the final case which had a personal connection with the characters. These last cases in every season were quite problematic for a variety of reasons, only season 5 had a better implementation despite its weak climax. More highlight across the seasons, the last episode of season 3 was the worst out of the entire series. The cloning plot in season 4 was super trashy and tacky, despite having an obvious playing room to take it into very interesting directions. The ending of season 4 featured another super weird and awkward kiss. The entire thing about AI in season 5 was really janky and a big stretch for the viewers to accept. In general, the cases were a mixed bag in every season, some were decent and interesting while others were boring, flawed or being stretched thin. However, season 3 featured mostly bad cases in addition to the handful of other problems which made season 3 to be the worst one in general.
The series as a whole was alright with a lot of ups and downs. It had a good concept with a varied degrees of execution. Although season 5 is the best one but it wouldn't have been that good as a stand alone drama without the accumulation of these characters journey. The ending of season 5 with both leads walking outside was very nicely done. On an unrelated note, it was impossible to not notice the ML's height.
