This is a completely hilarious show with an interesting premise that produces a queer leading character - a man in a woman's body. It's extremely unfortunate that the finale is such a cop out, which renders the entire show another example of queer baiting. This is an exciting roller coaster ride that at the end throws you off your seat to your death.

Spoilers below:
1. The king is explicitly in love with the spirit of the male MC, not the real queen. He noticed that the queen is out of character but did nothing. They’re now just another straight couple.
2. Is the MC bisexual now? Ending it this way makes it another queer baiting show. The writers are also trying to backtrack and say that both characters' souls are inhabiting the same body but remember how the queen's body almost died because the MC went back to the 21st century? The doctor said her body was in a soulless state. This is the only time where the queen's soul took back control of the body and their explanation is that she's in hiding all along? Also, none of the queen’s feelings for other characters stayed, not her feelings for her childhood friend/maid, cousin, or father, only her feelings for the king, whom she met once as a child, “remained.” But why? Is her entire existence anchored around her love for the king? The MC certainly rationalized it as the queen’s feelings when he first felt his attraction to the king. At the same time the MC certainly has enough control and agency to do whatever he wanted unrestrained by the queen's years of etiquette training, including acting on his attraction to women. Bullshit.
3. The original queen is literally the most useless character on the show but gets to reap the fruits of the MC’s labor. In fact, she is a(n abusive) damsel in distress saved by straight male MC. This is not feminist at all.
4. All the reforms they did led to an identical Korea in 2021.

Bad ending on all fronts. 0/10. Just don't watch the finale.