Definitely my favourite Chinese drama.
I found the beginning a little slow and sometimes confusing (because of the amount of stuff happening and all the names of the characters), but I kept watching and then I became addicted with it. This drama got me into danmei novels.

It's true that some points of the plot are different from the original one of the novel (see for example the 13/16 years), but it didn't bother me that much apart from the censorship.

Xiao Zhan and Wang Yibo are great actors, they were able to convey the relationship the main characters have in the novel even with the different plot. Xiao Zhan is the perfect Wei Wuxian and I found especially exciting how Wang Yibo was able to show Lan Wangji's emotions through micro-expressions and movements of his body.
The side-actors were very good too. Zhu Zanjin was able to make me hate his character (no offense to him though) and Ji Li is a perfect Nie Huaisang.

p.s. the characters are all dubbed by chinese "voice actors", so when you listen to the characters talking you're actually not listening to the actors you see on the screen

The OSTs are so good I made a playlist especially for this drama, especially the main theme.