I wrong a big long angry review after watching the first 4 or 5 episodes. It was almost unwatchable for the first 2-3 episodes -- terrible writing, cringe overacting, everyone's emotions were completely over the top, you didn't care about any of the characters, and worst of all, the main guy is just about the worst heap of steaming toxic masculinity ever to grace the silver screen. He punches and kicks everything, bullies everyone, and is one of the more unlikeable characters I've had the misfortune of watching.
Sooooo, it turns out, it gets better. A LOT better. My wife wanted to keep watching so I stuck it out, and I'm glad we did. The first truly great episode in my opinion was #7, which is almost halfway through. But from there on out it takes many twists and turns--many of them predictable (but still satisfying) and several others which caught us by surprise.
It probably helps to think of this show as being a bit like WandaVision, where the 1986 backstory is deliberately overacted and corny because it's (I'm guessing) mimicking the way Korean dramas/sitcoms were back in 1986. The characters, acting and writing all become significantly more mature as the 2016 timeline evolves.
To be fair, there is still some weakness in the second half: a bit of manufactured drama from characters not telling each other critical pieces of information, poor decision-making by the police crew, and even some straight-up melodrama in the latter half, particularly in the last 3 episodes. But it's forgivable because the story is really solid. It's a very, very good story, and the first 6 episodes were more or less necessary for setting up all the complex twists and turns it takes in the second act. Oh, and the main guy becomes much more watchable after the first half, as he matures as a human being. His toxic masculinity was intentional and it gets fixed as the story unfolds.
It's pretty obvious why there's already one remake, and it wouldn't surprise me at all to see a Korean or Hollywood remake at some point with a higher budget. It's a fairly unique story that's hard to pass up.
There are definitely some timeline continuity issues, and they leave more questions open than they answer by the end. So don't come looking for great sci-fi here.
But as a crime drama, this is about as solid as it gets, and my wife was bawling at the end. I might have had a sniffle or two. I'd rank this up there with Beyond Evil, Stranger/Secret Forest, and The Guest as one of the top non-romantic kdramas out there.
Long story short: Stick with it and you'll be rewarded.
