Okay, despite the bad reviews I've seen, let me tell you this.
I think the genre most fitted to Yeonmo is royalty and slice of life, with maybe a bit of drama.
We are shown how life is at the palace, how a young royal live their life against the harsh palace and grow up to be a benevolent and wise leader. It is serene, graceful, sometimes intense and filled with delicate schemes.
The cinematography and coloring is exceptional. Yeonmo uses a lot of flower and tree sceneries, bright and warm colors, and takes up a rather slow pace. A lot of the actors and actresses are young and new talents, but their characterization and chemistry are so good on and off camera! It's really refreshing to see.

Also! This is one of the dramas that portrays the purest definition of love. I absolutely loved it, you have to watch and see for yourself.

That being said, I think this drama is best watched one episode or two at a time, not to binge. There are minimal violence, I think, and no adult scenes (if you exclude kiss scenes which every K-drama have). Totally recommended!