I saw this drama on a few recommendations and lists so I thought to give it a try, plus I was following some of Lin Gen Xin 's reality shows and become a fan so...here I am reviewing this drama after I just finished it.
My basic rating...first off, the story was good. I did like it. I am usually not a huge fan of these major internal relationship struggles type shows but the story was good enough that I didn't think it was bothersome.  Apparently, it is based on a novel series so if I ever find the audiobooks I might give it a try but the audio language may be too hard for me to understand, sadly. Secondly, the cast was great. I have watched some other dramas that some of these actors have main roles in so I knew they were good, just didn't know whether their chemistry in their acting would mesh with their roles.  Sadly, I saw an article that a second season was announced to finish off the rest of the series, but the original cast might not be in it or at least the MCs will change actors. Changing actors half way is such an annoying thing, especially when the actors received so much positive feedback for their roles. But, you never know the situation might change...crossing my fingers, I find some announcement that disproves what news I've seen so far about the second season.  Third, music...besides from the OP, I loved the in-show soundtrack and GEM's ED.  I love GEM so when I heard the ED, I immediately fell in love with the song.  Lastly, rewatch value...I would love to rewatch it, to find any quirks after I listen to the audiobooks if I find them. There are always different presentation quirks between medias. Personally, I rarely rewatch long seasons, anything over 30ish is too long for me to stay focus while rewatching.  
I would definitely recommend this drama.  But, I do have my complaints.  I feel like the romance wasn't developed really well through the script.  It is either my Chinese language skills that hindered my understanding or they just didn't really move the romance.  The CPs had their moments but...It feels like you caught a fish but you can't reel it in and you're tugging back and forth.  Then again, this season was apparently only one and half books in the series so it might just be that we're not there yet which is why they presented it this way.  Secondly, the story didn't get good until the latter end of the drama in my opinion.  It was good but still boring enough where I would want to fast forward in episodes in the middle so...there's that.  Lastly, the ending is crap.  They literally made the ending to foreshadow the second season which to me is advertising to keep the audience. But, then again, by the end of this season, everything is pretty much wrapped up, but the ending just leaves me feeling empty.  I don't know. You'll have to watch it to understand what I mean.  I'm kinda picky when it comes to endings.

Overall, I recommend this drama.  It is the typical relationship struggles for power in politics, family, and love in a historical setting in palace politics and martial arts but the story is good enough to make you feel for each of the characters in the drama. You will feel for the protagonists and want to help kill the antagonists.  WATCH IT  ; )