Without spoiler:
this drama is really fresh, different, soo much funny and catches you from the first 10-20 minutes. there are so many things that are soo different from usual dramas.
what was great:
1. FL (though she kind of is ML) - character like who we haven't seen
2. phenomenal acting from FL. others are good too, but not near to her.
3. humor, oh God, I haven't laughed that much soo long
4. cliche and taboo free, for example I don't remember drama with so much sexual/intime undertones, they act so natural and show so real chemistry and sexual tension, passion...
5. very unusual story, I mean gender switching is normal in dramas, but there are so more unusual storylines in this drama, few times I was like "no way, they wouldn't goo so far..." but this drama really breaks many drama taboos
6. the whole mood of the show, with perfectly fitting music and acting, there are soo right mood, soo funny
.... there are many really good things too, you should watch )))

what was bad:
main problem is the end, 1-2 little different scene could be make this drama completely perfect.
Spoilers:
the whole story clearly showed, that it was only SY's body and then some memories, BH even blamed female body for wanting king. Even if there was some piece of SY which helped BH fall for king, the character we watched for 19,5 episodes was BH. King fell in love with BH and then changing him even and King didn't even noticed it... that's just not logical.

There was scene, when BH/SY says to that guy who loved her, that it's just her body and if he loved her how he couldn't notice that now this is different person, so same goes to king, even more because king was his husband and was all the time with her, so how he doesn't noticed?
Ok I understand if they would stay together and happy anyway, because he already loves her and even if noticed that she changed, he wouldn't just stop loving her in one day, would see her in good way anyway and get used to even new herself, it is realistic, on the other hand SY not saying "you know, I'm not the one you fall for" is realistic too, she loved king whole life. But at list they should show that king sees difference, is kind of confused, misses how she was or something like that. He loves his wife but misses something, that wouldn't destroy happy ending or anything.
We can't say that they afraid taboos or gay theme, because this drama had so many brave scenes, so much sex/intime undertones, they already showed us practically two males fall for each other. one gender theme was in side characters stories too. So why back at the end?