It's a mistake to take a supernatural saeguk too seriously. Parts of this were so hyper that it was quite funny. I kept wondering what the Ha Ram script looked like as he turned into various manifestations of the demon - what are the stage directions like? The changes certainly kept the makeup people busy. And how many times did Painter Hong say abeoji in this drama? Good grief. I'm very fussy about CG, and all the CG effects were well done.
This is possibly the most over the top historical I've ever seen, to the point that it became absurd. But it still provided pretty good entertainment. The cast did a great job, the writing wasn't annoying, it was a little over-long but not horribly, and even the music did not offend. It was fun to watch, and you could spend your time in a worse way - like watching Squid Game.