It's simply a very well-written drama with an engaging plot and excellent romance. The long episodes go by like a lightning, it's very well-made, with a complicated family in the center of it all living through two simultaneous crisis. Kim Soo Hyun portrays his most vulnerable main lead, it's such a great testimony to his acting. The secondary cast simply served, they are all charismatic and interesting in their own ways. I could barely see those hour and a half episodes going by. Streaming, INVEST IN YOUR WRITERS! Also the soundtrack is so iconic. Definitely a 10.