I have just watched the first 12 episodes and I am being on conservative side in my rating until I updated at the finale.
First I would like to say that beside Game of Thrones and Vikings this has the best musical and visual intro I have seen. It is a gorgeous artistic watercolor show with an antiquated flute drum soundtrack that had me captivated.

Next it starts off with what you think is the typical narrative of someone giving you an update of histories past....but shows your lead in a vulnerable comedic position. So it had me at Hello.
I have never watched an asian period piece with such a royal/Ruling family as this. You are not quite sure if they are dysfunctional or insanely intimate; but the relationship between the characters are what I like best.....deep..complex...intimate...clever and funny...but mostly loving. Most unique king prince relationship I have ever watched....loved it. I think so far the King/father is my favorite character.
The dialog is long and may put some off ...and if it does this show is not for you because the brilliance is in the dialogue and the mystery within.....and the actors are brilliant and portraying the most amusing characters.
The show definitely has a drawback and that would be the contrived brilliance and luck of the ML.(this was also only thing I didnt like in Joy of Life)..but due to the humble vulnerability of his character I let that pass. I would also love a little more feminine intrigue or storyline... whole lots a yang...not so much yin...but I see its coming. I love strong Female characters and the set has been staged for many.

I am thoroughly enjoying
the show is Very Good.... You can tell it is related to the makers of The Joy of Life.
Costumes...cinematography....actors ...music and editing...are so far brilliant.