First of all: so much advertising! I mean, at times it felt like watching an elaborate commercial.
It was really distracting and my main reason for the low score.

Normally, I'm super into space-time paradoxes (among my absolute favorites within the sci-fi genre), but this is messy and, most of all, terribly boring (I'm so very disappointed in Kim Eun-sook).
I fell asleep multiple times.
By episode 5 one can easily guess the masked savior's identity and still fail to understand the mechanics of the parallel worlds created by the writer. For instance, how is it possible for universes that diverged for hundreds of years to have the same people, born on the same year and day from the same doppelgangers?! And how does it make sense to base everything on this premise and still assert that a different choice or being a second late can cause chaos in the space-time continuum?!!!

Despite their individual talent, the main couple was tepid throughout. The characters were dull and their love just came to be so suddenly that it was as nonsensical as the plot.

At one point I rooted for the prime minister, she looked like an interesting one with her political schemes and feminine outfits, but even that fell to nothing.

Honorable mention for Woo Do-hwan that tried his very best here and kept me watching to the end.

Female Empowerment Score 3/5: the three points go to the cool building owner and, in a smaller percentage, to the prime minister lady.