This is my first review on here, but I just had to write one after seeing all the positive reviews and the rating for this show. They are not just positive, they are extremely positive with messages like "best drama ever", "masterpiece" and so on. I don't get that at all. Well, most of them are from 2015 and I watched it in 2022, so maybe this show just aged really badly. But I don't think so. And here's why:

Story: The overall idea of the many alternative personalities of the main lead is quite nice, I have to say! With this number of alternative personalities, so much would have been possible. But it was wasted, not explored at all. Instead, the drama was packed will all kinds of other things. It felt to me as if they wanted to make it a comedy, a love story, a mystery thriller and a story about a big corporation. And a doctor/patient story that educates the audience on psychiatric ilnesses. That's a lot. Probably not impossible but the writing here is just too bad and in the end, nothing makes sense. An example of a show, also including multiple personalities, where it made sense in the end and were the depth of the mind of the "patient" came to life is "Bad and Crazy" (2021). Also the other big aspect of the story, where they have a build-up of 18 episodes to make it appear as if there is a big dark mystery behind everything is weak, as they - spoiler alert - just don't deliver in the end. The biggest mystery to me was how I managed to watch this till the very end (self-torture, I guess ...).

Acting: the male lead is a phenomenal actor, but that doesn't help much if the writers and directors don't use his full potential. The female lead is horrible: overacting, screaming, crying like a baby, being happy like a kid - the child actor in the flashbacks was more serious than her! I have not seen her in other stuff, so I don't know if it is her inability or the director's choice! The writing for this character is definitely not suitable for a grown-up doctor and lover. Her character didn't bring anything to the story. The side actors are okay, no complaints here. I noticed the main female's dad and the psychiatrist professor as positive. However, the writing for most of the side caracters is, again, bad: the main female's brother really behaves like an a**hole the whole time (there is a 3-minute explanation somewhere in the end, that makes totally no sense), the male lead's mother, father and grandmother all are horrible people and there is little to no explanation on their behaviour in the end, the secretary is just like a dog that comes when called but is irrelevant to the story, same goes for the second love interest, and so on.

Editing: I noticed several times that the story jumps around quite a lot between places: one second they are all in his house, then her house then the company headquarter without a good reason and often without a proper segue/transition. And, but that's a K-Drama staple, overuse of flashbacks.

So, overall, I think there was so much potential, but it was executed so poorly. Definitley not worth 20 hours of your life!

Most memorable bits: Shin Se Gi's cheesy lines, Yo-na chasing after the idol and the brother (funny, but a bit homophobic) and the doctor ignoring al privacy standards without even blinking.