Excellent introduction to historical k-drama genre.

The korean acting style is a bit more broad than in the west, as are the plot points, but if you are able to get past it, then this one will captivate you. Timelines can feel a bit rushed as well.

At the core, it is about what it means to do good in a world where power takes on a life of its own. The consequences of your choices that cascade around you.

The performances of the two leads ground the story, as Choi Jun Seok has the presence of a king, while Shin Se-Kyung is beautiful and charming enough to believably have him fall for her, the weakest part being the cross dressing, as she is too pretty for it and a strong suspension of disbelief is required here.

Rest of the acting is above average. Plot can get a bit convoluted, as key points can be single sentences without emphasis, but overall the tension is maintained through to the end.
Writing overall is good and crafted to reflect the audience feelings of wanting to overcome the trials so the couple can just have a happily ever after.

Watch when you're in the mood to cheer for a bittersweet love in the face of political pressures.