This is an unusual series. I was not disappointed with this series at all. It was built around a prophecy that added that fantasy element that I enjoy a lot. What was most intriguing about this series is the question it asked regarding the relationship between the two leads Joo Won and Kim Hee-seon. Since this series used time travel as the main driver for the events, you'll definitely be left with a question that you never came across before. Even the writer himself was very careful or, in fact, uncapable of coming up with one. I believe that hurt the story a lot. You can easily feel how unwilling the writer was to give an answer and pretty much left it open even at the most important part of the series THE ENDING.
