I'm writing this at 5am in the morning, that should give a little bit of insight on how great this drama is, it really is on a level on it's own. If you are thinking of watching this, just give it one episode and I guarantee you will be hooked.

Story was exceptional, the way they told the story of the main character, the other prisoners, officers and more and what occurs in prison was entertaining and exceptionally done. Even the writing, the relationships build, the humor that was placed in all episodes was out of this world.

Acting/Cast - Every single person cast in this drama, it was as if they were made for the role. Great acting from the main leads and supporting roles.

Music - The music helped to set the theme and tone very well, I even liked the theme song a lot. But something that I really liked was when someone would sing a song for a scene and then they wud play it after. I liked those moments for some reason. Great song choices throughout.
Rewatch Value - Yes,  I would watch this again.

I really enjoyed this drama, before I started it, I didn't think I would enjoy it so much. It even made me cry, which is hard to do. I will miss it.