All jokes aside about how nice Muon's hair is, the story was a nice read. I had to double check for the smut tag as I was caught off guard by some steamy scenes that don't really show anything, but I certainly did not expect to see them.
I appreciate that the story doesn't drag and the struggle of the FL is presented realistically. The FL is tormented and her actions reflect that of a powerless person who hasn't yet been broken because they still dream of escaping. Her fears make sense, her hesitations make sense, her choices make sense, her trust issues make sense. Her emotions are all over the place but again it makes sense given her situation.
The story is driven heavily by the past and even the characters seem to understand that there is some truth to their kingdoms history. Aside from the female lead we really don't get a good look at the other characters, the FL's caretaker is kind and a pillar to the FL, the silent eunuch is sweet and a dear friend to the FL, the ML is the FL's love interest and the king is the FL's antagonist. The characters never really show anymore layers to their personalities besides that. But since the story is about the FL, the amount of emotional, mental and physical trauma she is trying to endure makes for good entertainment as each character plays a role in shifting her stability throughout the story.
Lastly I'd like to point out that I did notice Muon is quite attentive to the emotional and mental trauma of the FL, he often asked what was on her mind and took the initiative to try to openly communicate even when they both were keeping a lot of secrets, I don't see that often and thought it made him stand out as a ML.
Overall I don't think this book would be for everyone, but I would recommend giving this one a try, it certainly doesn't waste your time with fillers and it can easily be completed in a few hours.