The storyline is quite refreshing, and different from the normal romcom cliche.
Since FL and ML have completely different backgrounds, it's understandable that FL with shabby past family experience is hesitant to move forward in a relationship with the ML who comes from chaebol lifestyle plus also loved by his family (esp. his brother who is super supportive). The romantic and emotional lines are also heart touching.
I also like how it presents the relationships among the characters - FL and her little brother, FL's lit bro and ML, FL and her friend, the chaebol brothers, ML's bro couple and the colleagues. I laugh and cry a lot through out every episode. The mood is like riding roller coaster.