Sorry for the long review. But, I just had to rant on how much good this drama was.
First of all, this review is solely based on the remake, I have not watched the original version and I am not planning to watch it in future. I do know the plot similarities and differences between the shows.
Let's start with Jung Kyung Ho. I had always loved him ever since I watched Prison Playbook. He was impressive as Tae Joo. The way he kept his face straight all the time as Tae Joo was inexpressive most of the times - and the way he gets lost in thoughts and his despairs and struggles with trauma - everything was realistic. By the end of the drama, he had come a long way from being an indifferent cop to becoming a trustworthy friend. His trauma was in obstructing him from interacting with others which gets knocked down by the 1988 team.
Dong Cheol is my favorite character in this show, along with Na Yeong. I saw Park Sung Woong on a BL called Method and I have seen him in some guest roles, so I didn't have much idea how is acting was. But, this show proved that he was an incredible actor. Dong Cheol was street-smart and short-tempered, a stark contrast with Tae Joo. Still, the bromance between the two was amazing. They understood each other completely. I am impressed about the amount of swear words that came from DonG Cheol throughout the show.
I have never seen any of the shows by the rest of the main cast. Na Yeong was impressive. Unlike in most K-dramas, where female cops are mostly dumb and are bad in terms of fighting, Na Yeong shines by her intelligence, analytical thinking and insane fight moves. She is the only one to whom Tae Joo admitted his crazy time-travel story...which shows how much he trusts her. And in return, Na Yeong made him feel at home unlike others who initially were cold to him. Since this is the 80's era, women cops are rare - she is the only one who is wearing the cop outfit and she is always assigned to do tasks for the male cops instead of doing the police work. Only Tae Joo respects her and in the end, everyone treats her as a fellow co-worker than as their made. And though they hinted that they might have a relationship, I was completely fine with no romance, just like in The Psychopath Diary.
Nam Shik and Yong Ki shared a different universe altogether. They were a good as a duo and worked well as cops. Yong Ki was an asshole at the beginning but his character took a turn while we neared the climax.
Everything aside, Tae Joo had a loving family. Both the 80's era family and his present family cared for him. Tae Joo's dad might have been a jerk, but he was really a best dad to Tae Joo. No wonder his death affected Tae Joo so much.
Everyone has different theories on what happened, so here's my take: I think after coming back to 2018, he attempted suicide to be with his friends of 1988. Both the mom, ex-girlfriend and doctor wanted Tae Joo to be happy...that's why he chose the 1988 world. It might be heaven or maybe he really was in 1988, since Hyun Seok calls him. Which is kinda depressing, I laughed because Tae Joo was happy and cried because it hurt that this could be unreal.
I liked that when Tae Joo was in 1998, the narrative for the drama's intro was 'Am I going crazy? What happened?' and then when he was back in 2018, the narrative was 'Am I really back? Or is this a dream?'
One thing bothered me was Tae Joo went back to 1988 to know the truth about his dad's death, but I wished that he also could have pretended Min Seok from becoming a killer in the future. In the end, the victims of Min Seok still died.
Overall: 9/10. Minus 1 for making my head spin because of that ending.