That's the sense I got from the beginning of this show, it felt big headed and self satisfied, "please watch me, I'm so clever" Not.

This show tried its best to dazzle us with the mystery regarding how time can be manipulated and with mathematical wizardry, but unfortunately as the story progressed all of this clever potential was discarded by the wayside and all we ended up with was very poor pacing and inconsistent storytelling.

I consider myself to be adequately well versed in things like music, literature, world events, art, philosophy etc; so as a viewer I really welcome it when a writer presents an unusual and unique story, and I'm quite able to keep up with the events the writer is unfolding. But in this drama I was constantly scratching my head wondering 'what's going on now?" "did I miss something ?" "wait a minute who's that?" all to culminate in this weak ending that rendered all the confusion null, mainly because the huge amount of characters that were introduced came to nothing, were never fleshed out and their stories were minimised towards the end.

This drama took its viewers for granted mainly because the majority of people already loved it even before it began. There was a great willingness on the part of the viewers to forgive some flaws and go with the flow, but I think that the flaws in this show are unforgivable, for example the show has very poor structure and the chronology is all over the place ( I know this is supposed to be explained by the time travel/parallel universe premise) the story is all over the place, literally; As a viewer I was often plunged into scenes without a clue as to the context, thus the head scratching.
In my personal opinion, my real time experience watching this was not enjoyable because as I watched it episode by episode I never got to the point of enjoyment because I was always searching for clues to help me understand the story better.

The acting mention I can give here is for Woo Do Hwan, his scenes are always engaging and he has a depth of delivery that is impressive. I also like Lee Min Ho, he's not a bad actor but in this show, the intention was to make him look cool rather than to act well. Kim Go Eun is the kind of actress that will act according to the quality of her leading man and supporting cast, and I think she failed to shine here; I was also not impressed with how she was written, from a strong, confident police lieutenant to a weak, weeping, lost in love damsel, it was truly awful.
Prime Minister was atrociously written, I can tell she's a good actress but really Jung Eun Chae had no chance with the cards she was dealt in this script, It's a role she should have refused to play; her character's descent into the typical jealous, mean and spiteful spurned woman was so disappointing, because this was a role with so much potential.
Lee Jung Jin as Uncle Yi Rim was a waste of a good actor, he was so badly written with weak motivation and back story, it was sad to see.
Kim Kyung Nam had depth as Shin Jae, but ultimately it all amounted to very little.

This show had flashes of brilliance, the concept is intriguing, unfortunately it was handled poorly.

The rating I've given is mainly for the production value, the cinematography and the few flashes of brilliance, oh and Prime Minister's wardrobe.

I understand the OST is good, but I actually never became too familiar with the songs except for the one by Gummy. The music was not used consistently so that's another lost opportunity to build poignancy because music plays a big part in that.

That's all I have to say, sorry but no.