I'm not normally a fan of historicals. I feel like there is one script that they use for every historical, just changing the names and the actors - someone in the family trying to kill the monarch, evil people in power (especially high-ranking officials), scraggly beards and moustaches, beautiful costumes, ridiculous hats, sword fighting, kidnapping, bloodshed, mistaken identity, ginormous cast with multiple storylines. This drama kept popping up in my face, so I figured I'd give it a try. If you are die-hard fan of historicals, you'll probably like this. There is no doubt that it was well done, but there was so much filler that the fast forward button and I became very close.
There were many positive things about this drama for me:
The cast, especially -
Rowoon as Jung Ji Woon - do I even need to explain why? I find him to be very charismatic and his acting is understated. I can feel his emotions, and he tends to have very good chemistry with his leading ladies.
Park Eun Bin as Yeon Seon/Lee Hwi/Dam Yi - for me, she was the standout of this drama. I do not like the gender bender genre, because every single one that I have seen has a woman that is so beautiful that there is no way that anyone that can see at all would confuse her with a man. Her features are always soft, and they have her perfectly made up. Park Eun Bin was terrific in this role! First, her stature and her face are such that you could conceivably believe that she was a man. Don't get me wrong, she is absolutely gorgeous, but she was made up so that her face was all hard angles, strong jawline, no puffy cheeks. Add to that, she did a great job of keeping her voice deep, and she had that cold, aloof demeanor down pat. Her movements were very masculine when she was playing the man, as well.
Nam Yoon Su as Lee Hyun - I loved his characterization of unswerving loyalty in the face of having to deny his feelings.
Go Gyu Pil as Hong Bok Dong - He brought a little comedy/lightness to an otherwise heavy show. When I saw the child actor playing this part, I just knew Go Gyu Pil would be playing the adult!

Excellent chemistry between the lead actors. Honestly, if I were to re-watch this, it would be to fast forward through all the intrigues just to watch their love story.

Bottom line - I think that if historical dramas are what you gravitate to, you will probably really like this one.