Just perfect. Its been decades since I had NOTHING to complain on a story, but quite a lot to praise. I kinda want to leave my review at that but I'll add a little more.
All actors and actresses do a great job. Each character has a thought out backstory and a goal/behaviour that makes sense with that past/present. The main couple have chemistry, good scenes and potentially one of your fav CPs in fiction. All romances are different and real, without "drama love" being at all the series's focus - I would even say it doesn't really have romantic drama, since everything that happens is realistic. Realistic situations, realistic feelings, realisitc assumptions, for each character in the couple to have.
But the strongest point in this cdrama (but it's really all connected), it is the women. How every woman suffers in this time in spite of their position (from a pariah to an empress), chooses paths (or has to go along with a man's plan) and has to be extremely strong in different ways - and how they know what the other goes through.
It shows the sexism in all aspects and a true feminism, that isn't the woman being physically strong as so many other shows do. I don't know what's so hard about doing a commentary on this subject, but luckly they did it right. And it's not the bare minimum, on the nose, exaggerated nor has the goal to make the audience pity them. Geez, finally.