This drama series is worth watching over and over again. When it comes to story, its a fresh story, unpredictable, entertaining and gives its viewers suspenseful feel. When I'm watching this, I can't wait for the next episode to watch again. You will get hooked in each and every episode. When it comes to its casts and acting, i think everybody worked their part very hard and they blended very well in every scene. To be honest, I watched this because I'm a fan of Jang Geun Suk, and seeing him portray his dual role amazes me more. He did his role very well and you will never get bored in his acting abilities, and he really blend very well with his co stars especially with the female lead. I expect to see him more in future drama series. Speaking of the OST's, all i can say that they're all cool to listen. The music arrangement fits very well in every scene which made every episode more exciting. As a whole, you will never get tired watching this over and over again. I love this !