Story/Production:
The drama has many interesting characters. I think the reason why you most time felt the story being realistic is due the fact, that the persons really existed in history. The plots are entertaining and could keep you til the end , but it could have much better with such historical personalities as model.

Characters/Actors:
Besides of the 2nd sister and her husband (both acting were kinda too exaggerated), all actors were actually quite solid with their performances.
Out of the three sisters. They tried to make a strong female lead, who felt a lil bit flat. Due the story telling couldn't grow and build a connection with the characters growth at all. If I would have to choose out of the three sisters, the oldest sisters has more depth and the best actress.

The main lead fits very well as well.

Overall:
It was a drama, which had a lot of potential story wise, but got wasted despite having the budget. At the end it's an average drama in the higher budget segment.