I wouldn't know if anyone told me the plot and general preview of the story, for it to be kdrama. When you Think of romance genre in kdrama, you'd Think of puppy love or hard core plotting. This has a Little of both, which makes this drama mature, yet not too mature for it to be hard to follow...

OST
I wouldn't per say listen to it separately, but i like the mixture of Spanish, English and Korean. IT's nice to hear that type of songs, and they were well picked, to kind of tell the story of scene without having to make characters emphasize that's silently going on.

ACTING
I don't know much drames that Park Bo Gum acted in, but i loved how he potrayed the character in this one. You couldn't help but fall in love with him. I also loved the chemistry between him and Song Hye Kyo. She Oslo did an amazing job, and im not surprised since she's quite popular for good acting. Both actors made the characters réal, and made the audience feel their émotion. The side actors did well too, none of them did a bad job, and complimented the drama well.

PLOT
It would feel boring when told, but you'll find yourself loving it and being invested in it.
It basically tells the story of a lonely woman who's a CEO of a well known hôtel company. She goes to Cuba, and finds herself wanting to see a sunset from a picture she saw, in réal life. She has trouble sleeping so she takes sleeping pills but still goes, she gets lost and pickpocketed, but find the place where the sunset was shot, she there meets a man who saves her from falling, and they go around Havana... When she gets back, they both find out that the man is the employée of her company. They face hardships, and develop slowly but neatly, with other characters.
_________
I LOVED the romance, it's slow but it still makes you blush and smileys from their cute interactions. But at the same time it can take a mature turn, and make you worry. The romance, isn't dépendend on plotting, but the hardship of a famous and rich person, who's quite older, dating her employée. there are many romance side plots, and even a plot of her ex that makes him develop from trying to get her forcefully, to mathurins into someone that wants to protect his family.
It's a show, for someone who wants a bit more of slower romance, and romance that doesn't have cute and funny interactions.