This drama combines well two very good ingredients: the parallel worlds/time travel and the modern monarchy plots. It's funny (at the beginning), sweet and, at times, tearjerker. The main characters have a good chemistry and the secondary ones are very funny and well detailed. The story sometimes is a little complicated but nothing compared to other west sci-fi series with time travel or parallel worlds (take Dark as an example). I like the fact that the characters are both very rational. Also the main antagonist is well defined and convincing. The visuals are stunning. There are incredible landscapes and, besides the fact that there is some CG for the Kingdom of Korea, everything is very pleasing to see. The soundtrack is fine, maybe it could have been a little more complex. The last part of the serie is a little bit different from the first part that I enjoyed more. Nevertheless this is a must watch!