I am surprised that Wedding Impossible got a better rating than the Impossible Heir.

This is a good series, if you watch each episode attentively. My observation and opinion of the series.

The story does not drift from its themes.
There is a reason for the main characters forming a friendship. Their lives had similar beginnings.

The FL's character portrays that she is not one to be swayed by her emotions. She does not show how vulnerable she really is. She is unaffectionate, and does not depend on any of the male leads. No one can guess what she is thinking or feeling. Hence, her team leader disliked her, because he could not read through her. (This gives the viewers an understanding of her personality) This is probably why her acting is criticized.

Male lead, Tae-ho. Character portrays that he is naive but strong. He is strategic, but desires nothing. Everything to him is about survival.

Other male lead, In-Ho. His character portrays that he wants acknowledgement. Viewers are already introduced to his attention seeking personality in the first episode (stealing and bulling) yet his attempts still does not get him the acknowledgement he wants. Furthermore, his insecurities arouses his jealousy of Tae-Ho. His friend should stay below him. This is also introduced in the first episode (0.1% in the national mock test exam)

All the supporting actors were good at their roles, especially Kang In-Ho's sister. Loved it.

Music, I really don't pay attention to music in series.
I never rewatch any series I've already watch.

Overall series. Like every story, this has themes, climax, and a thoughtful ending. This is a good series. Watch it on Disney Channel to perceive it yourself :)