Well I'm not into essay type things,,, so for me the best part was the acting . I'll say if you want a little bit thrill it's good too go but don't expect too much as I did . The concept was very interesting and had much more capabilities but they decided to keep it simple and short yet not disappointing.
As for the cast Woobin as 5-8 is the best thing tha can happen (he is the actual reason I started this drama). Sa-wol's character development was a bit confusing to me (as normally he is portrayed as smart but he did some stupid things) still him and his friends were one of the good parts .