I can finish this review in one line. Great story, Outstanding Acting, Amazing Music, Extremely Re-watchable and Perfect Overall. I really like dramas that impress me beyond their promotion pictures or a raw summary provided before its premiere and dramas that involve a story of revenge and betrayal because these two emotions contribute extremely in the suspense and anxiousness of the story that keeps you hooked and if you're hooked then those actors, directors, crew members etc. have succeeded. This drama had everything I wished to see. Park Si Yeon did an amazing job of making me hate her by acting SO real. Song Joong Ki portrayed the two sides so well that I was intrigued by both 'bad and nice' through out. Moon Chae Won is an all rounder with that perfect Korean accent and soft soft-spoken, calm voice she has. Kwang Soo and Yoo Bi, Yang Ik June, Lee Sang Yeob and Kim Tae Hoon were best at their roles. The prolonged title is very attractive."Sesang Eodiedo Eobneun Chakan Namja"(A Nice/Kind/Gentle/Good-hearted/Pure/Innocent Man,the Likes of Which You Can't Possibly Find Anywhere in this World). The OST has touched me very personally. It has the element of throwing away trust, taking the blame in love, loneliness, melancholy, change, darkness, chaos, calmness in every little thing in life, protection and the feeling of impatience for the sun to rise all night. It sets the mood of the drama and keeps you trapped. I will watch it again because I was not disappointed for even a moment. It is just my kind of genre. I hope you'll be touched by it. Go now. Watch it. :)