Wow! What a masterpiece! Where should I start from?!
The ACTING was amazing especially Ji Chang Wook. Almost all actors did their best to portray their character. I could deeply feel for each of the characters, even the worse evil ones. The strong point about this drama was that except Wang Yu, none of the characters were idealized. Each character had its own reasons and attitude. Nobody was completely right or wrong. Even the reasoning and arguments of main evil character seemed logical sometimes. Except Wang Yu, each character had interesting and exciting aspects and time to time you may have different feelings about them.
* Wang Yu was too perfect from the first second to the last and this made his character boring. Actually they should have left some space for him to develop.
* Empress Ki was really, really admirable. The strongest female character I have ever seen in dramas. She was a perfect warrior as well as being extremely wise and very attractive.
* Emperor is the character that distinguishes this masterpiece from a lot of dramas of its type: A very weak and hopeless character that at last becomes strong and wise. A really great and amusing character development that also shows how great was Empress Ki that had such an intense effect on him.
The STORY was really great, almost never got bored because each time another surprise came and I got shocked. It included interesting and intelligent plots and there were a lot of times I said "WOW! How could they ever think about such a plan?!". Empress Ki's plans and efforts were really impressive. It assures you that she truly deserves such a high position.
The ROMANCE was really intense and complex. Until the last episode I was not sure about Nyang's true feelings. That made the romance part really exciting. The weak part of a lot of romantic dramas is that after leads find out their true feelings, it gets boring and you just wait for the potential happy ending.
I believe that before strong romance, close friendship should happen and deep love without personal interactions and close friendship is just a fictional subject. To summarize, individuals should spend a lot of time with each other for the love to grow and get deep. This drama confirms my opinion.
Even if the romance is not the only and most important part of the show, but you will watch a satisfying and intense romance that makes you think about the emotional interactions between the leads.
The MUSIC was good and satisfying but not perfect. Actually after Moon Lovers I hardly accept drama OSTs as perfect.
About the REWATCH value, this types of dramas that are highly based of unanticipated incidents and you mostly watch to see who would win the struggle this time, rewatching is not a usual desire. I would also not rewatch it completely but because of the complex romance I will watch scenes with interactions of main leads for the second time.
The ENDING was wonderful one. Now I feel it's not important if ending is happy or sad, it should be meaningful. Not a simple and ridiculous happily ever after ending and not a sad, awful and what-the-hell-has-happened one. A really satisfying ending. For whom is hesitant to watch because of the ending I strongly recommend to try it.