1 star for the male lead, 1 star for a potential story line
-1 star for plot holes, -1 star for female lead (very annoying and does not respect others' space at all, jumps to conclusion, ignorant, how come the revenge plot was left in the middle conveniently?), -1 star for the annoying friend / 2nd ML (taking other's work's credit for self and then considering yourself a moral being and far more than that! His character was too hateful right from the 1st episode), -1 star for and the sister of ML (why bother yourself with a guy who does not know your worth and ruin so many lives!?), -1 star for ruining a potentially good story (very poor execution)
Overall score: absolute(+2 - 5) = 1 stars
Do not watch this drama if you don't want to kill time. No, even then don't watch it!