The first half of the series consists of a very good mixture of historical suspense and love story. Yeo-ri is a likeable, warm-hearted character, observant and smart enough to be believable as a young woman with a complicated past and the ability to see ghosts. Gang Cheol, on the other hand, is arrogant but he brings a lot of fun into the series, and, of course, he has a soft side as well. I enjoyed some of the supporting characters, too.
As it happens with lots of Kdramas, the second half falls a bit flat. There is much more room for character development, but instead of deepening the stories of the more important ones, the plot of the main villain - a gruesome spirit tormenting the royal court - takes all the room to a point where some character decisions don't make that much sense anymore. It's a lot of revenge and hatred, the emotions are just way too obvious and simple, and simplified stories like that always bore me a bit.
The world building is superficial in the fantasy area as well. Without going into detail to avoid spoilers, I feel like some things only happen for plot twists and drama although they don't make much sense. Even fantasy needs rules and logic. E.g. Gang Cheol and his friend are deities, not humans, their perception of the world is supposed to be totally different. Based on that, their behaviour and decisions should be a bit more complex, but apart from their powers and the funny things like court etiquette, I don't believe them to be some kind of superior being. But then, there are written by humans, which shows most of the time in this kind of series and movies.
I still enjoyed some characters and character dynamics until the end, and overall, it was a good series with an interesting story.
