Story/Production: different view + too many episodes
Many historical dramas are telling about the fights in the harems to gain the emperor's favors, where the heroine is slowly climbing up to the ranks of an concubine. There's a lot of killing, conspiracies, betrayal etc. The drama got all of this, but the thing, which they did different, is actually to focus it with the view from the losers side walking the opposite way. I think that's one of the things, which do stick out and keep the interest of the viewer.
The production is decent for the budget, but imo they could have condensed it much more into less episodes.

Characters/Cast/Acting: miscast
The character of emperor I felt is probably the more realistic approach. Did he like Ruiyi? Yes, but does he love her unconditionally? Nope, he's an emperor and he got many wives. I actually prefer this over the fairy tale image, which could find in many other emperors from other historical dramas.
The FL character is depicting someone, who wants to hold on their own morals and beliefs despite being in such a gruesome palace. And unlike most happy go lucky fairy tale ending, it showed a more realistic, what you sometimes have to pay as a price.

I actually like the characters and I would say that both FL and ML are actually competent actors. BUT I felt they didn't completely sunk in their characters and blend in completely. Wallace Huo couldn't convey the emotions completely imo. And he somehow gave an aura more like a master from a rich household than an emperor. Zhou Xun is having a too mature vibe and acting, for such an innocent or even naive character. Not her fault and probably the stylist's, her lips were also very distracting due the make up.
All the side characters and actors weren't every oustanding in my eyes, so there isn't much to say from my side.

Overall: A drama with a more realistic approach and focus on the "loser's" side, but could have done better with different main leads and shortened amount of episodes.