This drama is an entertainment void. Absolutely not fun to watch, the acting isn't the best, the vampire plot is handled terribly, it's a nonsense slow burn and even the real life marriage that came out of it didn't work out.
I thought the villain would add some seasoning here but, no. The premise that vampirism is a disease is interesting but it's for nothing here. The writing doesn't know where it's going, Goo Hye Sun's character is really annoying and the romance here has to accommodate for the plot which is very tiring to watch. It's like you're in a rock festival with a very bad band as the opening act but then the actual band you came to watch sucks a lot, so you just wonder why did I come here?
Some characters are charismatic but it's absolutely not worth it. I tried to finish this so many times until I realized it was literally torturing me. Just go for something else. There is no shortage of good vampire shows to watch, even if you want something campy.