I love the OST in this drama and that's something that only happens to me in korean dramas I think it depends on the person but personally I think it goes well with the drama, like kat797 said it has a melancholic melody that I can't get it out of my head ^^
A solid 9 for me, I didn't have to many expectations because of the comments but I liked the synopsis so I gave it a try and OMG I LOVEEEEEEEEEEEEEEED IT!!!
I thought I wouldn't like the series because of the comments in this site but I actually love it! I binge watched all the episodes in a few hours... O.o
https://www.youtube.com/watch?v=i6RQb1vuGSo