Originally I gave this a bit higher of a rating but looking back on it, it's more of a middle-of-the-road, mediocre drama.
It's not that it's bad; it just has so many clichés and isn't super interesting. The story is a bit slow, and not surprising. There aren't any twists or turns or suspense really.
The acting is great (except for a few characters that fall a bit flat), and surprisingly the chemistry between Park Shin Hye and Yoon Shi Yoon is great. Now the chemistry between all the other actors is....again middle of the road.
However, I do think it's a classic Park Shin Hye and Yoon Shi Yoon drama that everyone should watch if they are fans of those actors. But overall it's not a super impressive drama.