If you remotely like East Asian productions in general and Korean ones in particular and are a fan of the horror and zombie genre as well, this one is for you and not to miss. Add to that a historical setting with many subplots and subtext, and you get an idea of what kind of complete package this series is.
The only bad thing I could say about it is, that it ended after just six episodes and only half the answers were given with me wanting to get more of that show.
Strongly recommended.