Kwon Yuri's a poor widowed princess while Jung Il-woo is a widower of an unfortunate noble family. They are the most interesting couple I've ever seen.
Moreover, this drama is able to show the dark side and the light side of human beings at the same time. Everyone, even kings and nobles are important to each other. But they do their best for what they want, even if they make mistakes.
I love this whole story It can reflect the truth of human beings who have never escaped from their passions.