Although I understand that this is a 'version' of the original series, but it's poorly rushed off. It contains almost identical plot overall, but felt like they cramped storylines of several seasons of the original into this 20 episodes. The impact is directly on the character development. While in the original we came to see each characters' personality smoothly within each episodes, this version didn't show enough of them for us to understand why they act that way and it makes them somewhat annoying for people who didn't watch the original series.
Not only the storrylines are cramped, the characters are also cramped. They tried to make Kihyung to be Gideon and Hotch at the same time. Sunwoo is supposed to be like Prentiss but she's lacking a strong impression that Prentiss had. Nana is supposed to be the equivalent of Penelope, but like I said before because the storyline is rushed off, I didn't come to love her character as I love Penelope's. While Hyunjoon's character brought a fresh air because they didn't copy paste Derek Morgan ibto him, but they made him literally stole the magic charm on that train episode which supposed to be Lee's time to shine (He's supposed to be the Spencer Reid) because it was one of the best moments of Spencer in the original series. The rest of the cast just feels like a background to me.
To sum it up, it's the equivalent of making Avatar's whole book of water into The Last Airbender.
