The first is the story. The story of this drama the story is well made. The second is Acting/casting. I like the Cast of the show especially IU, why? Because the way she portrayed her character is so good and I also liked all the cast the way they portrayed their characters is not only good but GREAT! The Third is Music. Boy The music really fits the drama especially the song "Rainbow" that song is the emotional moments of the drama. The Fourth is The Rewatch value. I gonna say this, I gonna admit it gets a bit boring in later episodes but when you try to understand the episode then you will enjoy it I watched this a lot of times already, and it's not boring at all. The Fifth is The Overall. Overall the show is just so great the writers of this show should be given o much credit because the way the flow of the drama is the flow is slow but I think a slower flow is better for this drama I personally hated slow-paced dramas but for some reason in this drama, I liked it But recommend this drama I personally enjoyed it and I hope you guys enjoy it too.