I can't believe how much I love this drama... The characters feel like real people that actually have impacts on everyone around them. This is awesome because many times writers of dramas tend to forget characters that aren't in the main couple/triangle. I love that this drama shows actions and reactions of so many people, all while being able to keep the viewers absolutely in love with the main characters. No one felt overshadowed or forgotten, and you can feel how everyone involved really cared about telling this story. The cast is filled with some of my favorite actors of all time, so of course the acting is superb. The mark of a great actor is that you completely forget that they aren't their characters while onscreen, and the entire cast pulls this off perfectly. As for the OST...probably the best I've ever heard. This is the first time I've purchased music from an OST, and I bought not one, but two songs from this drama. One particular song is used to drive the plot further emotionally, and in the two biggest scenes it's used, it works perfectly to really capture the viewers' entire being into that scene. Those scenes hurt so much, yet I found myself watching them over and over because of how heartbreaking they were and beautifully they were put together. I already want to watch it again, and I've just finished! This has definitely become one of my favorite shows (not just kdramas!) of all time.