After seeing the high ratings this drama has on pretty much every platform I had pretty high expectations and was unfortunately kind of let down.
While the beginning (especially the first episode) starts off pretty strong, the drama soon wastes most of that potential within its first 4 episodes. A bunch of strikingly different characters are introduced very quickly, but instead of deepening their characters with detailed looks into their past the drama just gives a few superficial (and pretty stereotypical) glimpses of their backstory and never really developes past the characters being rather one dimensional and predictable. We have Sieun being a psychopath, Suho being a loyal, but mostly unserious cool guy and Beomseok... well, he is just kind of there.
Many interesting characters disappear as fast fast as they appear (for example Seokdae) and instead of taking their time to develop the story through more subtle changes of character we get fight scene after fight scene, with characters unrealistically changing within minutes and crossing, double crossing, triple crossing each other faster than you can blink.
All of what is happenning in these 8 episodes could have been easily spread over 16 or more episodes, giving more backstory and letting friendships (and enemyships) develop more slowly and naturally (and not pull so many last season of Game of Thrones moves).

The reason my rating is still relatively high after all this criticism is that nonetheless the acting is pretty good, and the teenage angst, insecurity and despair to belong definitely is palpable. And although the story seems rather rushed, it does keep you on the edge of your seat... even though that is mostly only thanks to the shock value of the extreme violence depicted.
Besides that the use of music is subtle, but effective, the show is beautifully shot and the fight scenes are well choreographed.

Overall it's not a bad show, just not as deep as people make it out to be, and not as interesting as to justify its astronomically high ratings.