Regrets.
If you're familiar with Greek mythology and the whole story about Sisyphus, the title gives it away. Yes, this is the main, consistent theme. Would you go back even if you knew it would repeat all over again?

I've watched so many time travel dramas but there's something about Sisyphus that's so addictive. As many already said, Sisyphus contains some nonsense/plotholes and it's already expected that the bars of logic have to be significantly lowered. While it did frustrate me sometimes, it didn't take away from the story itself. You keep wondering, "How is a badass and a genius going to save the world?" Also, props to PSH and CSW for their excellent performance here. I think they had amazing chemistry (with the subtle romance here and there later on) and worked really well together.

You have to enter this drama with an open mind. It might feel draggy at first, you feel confused from the start, you question if everything is pre-determined, there's so many "what the hell" moments and it's push-and-pull. And I think that's what makes this so intriguing. If the "title" is really true, then how- if- could the time loop really be broken?

I think it's best to enter it blindly--don't reach too much into the reviews. While there were some regrets in the drama (the many inconsistencies in the writing), the great production, cast, and storyline saved its grace. The visual effects and CGI might be a bit lackluster and the plot armor is just glaring, but I still really enjoyed the action scenes. Cinematography was top-notch and the thrill was enough to make me hold my breath. And, I cried--maybe a lot more than I expected.

Sisyphus used a familiar genre but pulled off something fresh and unique to the table, ambitiously at that.
No regrets.