OVERALL Very good drama, one of those that make you think and leave you on the edge of your seat from beginning to end. Watch if 1) You're looking for hot guys, 2) You want something addicting, 3) You have a strong heart. Don't watch if 1) you're looking for a love story (quasi-inexistent in here), 2) You're very easily scared. THE STORY I have to start by saying that my review is entirely biased by the fact that I am one of the most fearful people on the face of the Earth.That being said, objectively and subjectively speaking, this show is awesome. When the story starts, you think that it's taking one path, but soon realize that it's taking an entirely different one. Far from feeling cheated, you realize it makes perfect sense, because the drama asks one question from episode one, are monsters born or created, and its premise is to leave you to decide of the answer when the show's over by making your own interpretations of all the events and of the ending. There is no particular flaw or mistake in the plot elements of the story. All characters have their distinct personality and a dark side that slowly comes to light. Their interactions are really important, words are chosen with lots of consideration. Many philosophical questions are raised. The purpose of the drama is to make you think, more than anything else. It's deep, it's intriguing, it's terrifying, it's addicting, it's everything a show should be, but I personally had a hard time while watching it. Spent many sleepless nights. THE ACTING Very good acting. At the time, I think many of the actors were not quite known, but now they've played in many dramas (Kim Woo Bin, Sung Joon, Kim Young Kwang...). What's great about this drama is given how complex the characters are, how everyone seems so innocent at first and then slowly reveal a dark side, and given the story and the range of emotions that they go through, the roles demand some skills, and none of the actors failed to deliver. THE MUSIC Great music for the show. Many songs are in English and they fit right in. Being a fan of classical music, I knew Vivaldi's Nisi Dominus before White Christmas. Haven't been able to listen to it after this drama though. The show converted it into one of the freakiest tunes. REWATCH VALUE It's so good, that unless you're fearful; you'll watch it more than once. And even if you are, you might end up watching it again, like me, to show its awesomeness to someone else. But after a while, it might lose charm, since a lot of it rests on the element of surprise, that you won't have anymore.