Let's go from the beginning. From the start we can see that our main character Tae-Sul is basically a brave genious with some trauma from the past, that's yet not revealed. But also we can tell that the CGI is gonna SUCK, like really badly. But I mean, that's something to expect from a Netflix series.

Then it gets.. Confusing. Of course, that's not surprising since this drama revolves around time travel, something so complicated. But usually, as a viewer, eventually you should began to understand certain rules and things that revolve around the plot but here.. That's impossible. I think that not even the scriptwritters themselves knew what's actually going on. That's on just lazy production that doesn't even check what they have done and release whatever comes out of it.

This confusion goes on, together with you potencionally loosing interest in any of the main characters. Tae-Sul becomes a scaredy coward that just forgets how to think, only thought in his mind being a pretty girl - AND I'M TIRED OF THAT. Can they make a character that actually thinks like a normal human being? After few days of getting to know each other, he cares more abt her (Seo-hae), than anything else (aka the rest of the goddamn WORLD). Cute thought, but annoying only when implied.

From half of the series, it does (to my surprise) get worse, villian becoming the only normally thinking character, making him the most likeable out of all of them. Not to mention, by then we have been introduced to so many new side-characters, that we and also the producers, forgot about the ones that have already been there (such as the injured bodyguard), who suddenly appears almost at the end of the series, just to say two sentences, open more plotholes and give something to our main character (obviously they just randomly chose him because they needed to fill other plot holes they have made before that).

I could just go on about these things, the only time I actually was touched was when we found out about Hyeong-Do's daugher or when it seemed that Sigma (villain of the story), is gonna get his redemption arc.

BUT THEN THE ENDING RUINED IT EVEN MORE. It doesn't make any sense! How could Tae-Sul and Seo-Hae be together, when in that timeline SHE IS NINE YEARS OLD?! Like, what? Did Tae-Sul create the Uploader eventually and Seo-Hae moved even further back to get to know him earlier and start dating him? How does he remember stuff that didn't even happen yet? Did they travel to the past together, even tho the Uploader didn't happen? Tae-Sul killed himself, how is he alive? Why is Sigma still evil, how does he know about the stuff that has happened thru the series, even tho before that he didn't (he isn't supposed to know these things yet)? What kind of cliché-a$$ ending is that? Obviously, it's sloppy ending, rushed and written without any common sense! Just to leave an open ending with possibility of continuing the series.

If you were thinking abt watching it, DON'T.
Unless you are looking for something to waste your time on and pottentioly get a headache.