This drama was pretty much exactly what I've wanted from all of the historical/fantasy cdramas that I've watched (and not always finished) in the past.
It has smart and good characters, who go through an actual journey and have growth throughout the show. I also liked the fact that the writers never sacrificed how smart/cunning Li Ni and Cui Lin were for the sake of the plot. Things went wrong, but not because they were stupid and made poor choices.
The story itself was really enjoyable. It held my attention and had good pacing (something that lacks in a lot of cdramas imo). I also liked that while main story points were finished off and new ones took their places, it never felt forced or weird.
Even though I liked the tone of the show (it was light and serious when it needed to be, with just the right amount of angst) I do wish that characters/plots were allowed to be a little darker than they were. For example, I would've liked to see Miss Gu be more sinister and cunning to get her way. Same for the main villains--let's see them being more EVIL!
Lastly, while I really liked the ending, I do wish the climax was a little more intense. I wish that we'd built up to it more so that I was on the edge of my seat, but for what it was, I did really like it and how it played out in the end!