It is a nice series to watch, the acting isn't bad.
It's just that she could have ended up with mr. On. He treats her nice, he loves her, he respects her. But in the end, as any other k-drama, she chose the male lead, who rejected her twice and the moment she started dating mr. On, he suddenly started loving her.
I would have given 5 stars but I have given 3 because I still can't get over the fact that she chose male lead.