I recommend this show for sure. ( SPOILER ALERT )
When I first watched the trailer I was not intrigued because I was thinking a high school zombie show would have many flaws, but this just blew my mind and I just loved it so much.
The Good (95%)
Firstly the plot felt really new from all the Korean zombie movies I had watched like Train to Busan and Alive. The whole idea of actually fully understanding the origin of the virus was good. I also like the half-zombie idea as in real life viruses do affect people in different ways, which also explains why some people took longer to turn than others. The gore was honestly top-notch and we got to see the full features of the zombies. I feel that all my questions were well answered in the movie as making things too plain would kill the suspense of the movie.
I love the characters so much and they acted their roles well. The chemistry between them was great and the romance was not overdone. We got to understand each of their personalities and how that got to show for better or worse in a crisis.
I felt it a lot with Na-Yeon. Though she is childish, petty, out of touch with reality, and killed Gyeong-Su, she isn't necessarily a hopeless character. She really wanted to change and risked her life to give people who she knew would only reject her food so they wouldn't starve. I felt bad, (though I know she deserved it) when she died after only a few seconds of trying to escape.
Despite being a little far-fetched, the character Cheong-san was honestly inspiring, he cared more for saving his friends than himself. Sometimes the fear of death would make one do things one could never do before, and I think that explains Cheong-san's agility, speed, and strength. His death at the end was so sad to watch but not surprising as he showed countless times in the movie that he would sacrifice himself for others.
The science teacher made me very uncomfortable at first but later we realized that he is not so inhuman. Bullying is honestly one of the most heartless things to do to someone especially as it occurs mostly among kids. The fear, pain, lack of friends, or fun year in year out must be horrible to watch a kid go through especially when you see his classmates living normal lives and have no care in the world. He felt his approach would work, but even when it didn't he tried day in day out to fix it and even tried killing his family.
The Bad (5%)
There were things I wish they did better with the story though.
On-Jo's dad surviving all those bullets for such a long time was unrealistic, they should have made the distance shorter and the escape not so elaborate.
I wish they did more with the detective, he had such a promising character.
The commander killed himself for absolutely no logical reason. He should be more ashamed for not rescuing perfectly normal kids than bombing already dead people. Because of him, 5 fully alive characters died.
Final note: I don't wish for a second season. Not because it doesn't deserve another, but because they have already rounded it up nicely, and pushing for another season could mess things up.
Personally, this is the best zombie show I have ever watched and I was never bored ( well the adult's parts were, kind of...). The characters were well cast, fit their roles perfectly, and delivered nicely. Many fresh ideas in the script.