I'm totally obsessed with this show as well! It has a nice balance between being romantic vs. political intrigue focused. Plus Chen Kun's acting is quite good. I was put off at first when he was "acting naive" in front of his brothers, but perhaps his "act" was supposed to seem like an "act" for the viewer's benefit. His acting really shines in the later episodes when he's just being himself. I recently watched Babylon Berlin, and like this show it has beautiful cinematography, morally grey characters, great acting, and an engrossing plot too. You should check it out
This is an interesting point. I took a look at Ninja Reflections' translation of the ending for the book and they had a happy ending where Ning Yi left the crown to his younger brother and went off to explore the world with Zhu Wei. I actually feel like that is more in line with his character. We see throughout the series that Ning Yi was primarily motivated by 1) getting justice for his wronged brother Ning Qiao and the people affected by the witchcraft incident and 2) reshaping the government to be fair and benefit the people via a strong justice system. Achieving # 2 doesn't necessarily have to mean that he needs to be emperor, especially since Ning Ji had the same goals and initially sought him out for advise on ruling (in the book).
One thing that I'm confused about that I wanted to get the groups' opinion on: In episode 18, why did Ning Yi have to kill the stableman? Was it premeditated or just something he did out of rage? Did he not want the stableman to confess to the Emperor that he had planned for the stableman to kill the crown prince? Was it to punish the stableman for all his previous evil deeds (basically being a hitman for the crown prince)?