Overall it was a good drama. Had a few sweet scenes between the main leads. But, the ending just made me rethink and rethink how it could have been rewritten. As others have pointed out, if they had probably ended the drama at 18 or even 19 it would have still been ok. I just didn't like the ending.
At the end, I really felt sorry for the girl. King Wan So should have given up the throne for her if he loved her so much!
Music was good. Quite a few memorable songs.
Just watch it of you haven't, but be prepared for a cold ending that leaves you wanting more or maybe even frustrated like me!