I watched it with low expectations because of what other people's reviews about it, but from an unbiased point of view, I personally didn't find it that bad. I think that there are some draggy parts but the premise is quite interesting, and the plot was okay. The ost didn't stand out either. The acting wasn't amazing 100% of the time, though I think that the writing also played a big part in making the drama not as good as it could have been. I think that the best part of the drama is Woo Do Hwan and his characters Jo Yeong and Eun Sop. They're definitely my favourites and allowed Woo Do Hwan's acting skills to shine. I also liked Kim Kyung Nam's character. Another issue is that there are quite a lot of plot holes and not all the loose ends were tied up. One thing to note is that my friend watched it on a website where the location (Kingdom or Corea or Republic of Korea) and year were not shown so she was quite confused. Since I watched it on Netflix and the year and the location were written, I was not as confused and so I enjoyed it more than her.

TLDR, in general, the show was alright and if there's any reason to watch it, it would be Woo Do Hwan and his characters.