I dont know why this drama is underrated but as for me it deserves more than this. I was reluctentto watch this drama at first because of the negative reviews. I took the initiative to watch it coz it'salready downloaded and was consumingmy memory. And let me tell you it's worth it.
All the actors did a great job.

When we consider the story and charactors, it's quite unusual. The ML is obsessed with is so called sister. The FL is annoyed by her brother(not really).
The obsession of the ML unintentionally causes FL to hates him. But actually both of them love each other. They strive to be together even between all the hardships.

Sometimes the behaviour of the FL makes us unconforable and annoyed. But oveeall its one of my favs