What made me love Mr Queen was how the romance between Cheoljong and the Queen (who isn't really the Queen) crept up on me while watching the show. When I first started it, I didn't think I'd last long because I usually prefer romances. But then... BAM! They took me by surprise and it was delightful!
Never had I watched a K-drama that had dared this much in relation to gender and sexuality, so I immediately fell in love with the drama.
However, it didn't come without its' flaws.
I didn't expect a happy ending. Eventually, Hwan Bong would have to leave everything and everyone behind, of course. And that's just what happened.
The expected "no-homo"ness of it all resulted in an ending where they try to trick you into thinking it was a happy one. I'd prefer to think that the interactions between Cheoljong and the Queen with Hwan Bong in her body were all genuine, it makes the story much more interesting and powerful. You can't just sit there and tell me that it wasn't all real and that Cheoljong fell in love with the Queen, actually. Not only that, but that Hwan Bong's feelings for Cheoljong only came from the Queen's soul that lived inside her body.
Still, it felt like the creators pushed for it, but I bet they couldn't make the ending a more satisfactory one due to censoring reasons.
The ending had to be at least bittersweet for it to work (considering that Hwan Bong *had* to go back), but I wish the bond between Hwan Bong and Cheoljong had been spelled out better for the viewer and recognised for what it was.

Besides that, I have to congratulate Shin Hye-sun for her portrayal of the Queen, this is by far the best performance I've ever seen in a drama. She ate and left no crumbs. I also enjoyed Jung Hyun Kim as the male lead, I really like despite of all the controversies lol.