To sum up:
Not as good as the promo materials, but might be the best xianxia out there.
The trailer doesn't really do justice as it barely shows the beautiful cinematography.
Fast paced.
It's the best xianxia in terms of cinematography, visual effects, and acting.

Tantai Jin was not a typical xianxia's demon lord. In the early stage, he's more of a psycho in a xianxia setting. It's not easy to bring this character to life as he had no precedence in c-drama world. This is not a straightforward "love melt the demon lord's heart" trope as ML had a problem to function like normal human. It's a difficult character and cannot be compared with other xianxia ML.

In fact the closest character to Tantai Jin is not in c-drama land, but Hannibal from the tv series. Not saying Luo Yunxi's acting is Mads Mikkelsen level, but there are many similarity in the way the show managed to make the audience nervous on whether or not the main character was sincere or just faking it. This is the most terrifying thing about these characters and this c-drama managed to present this element to certain extent.

In Hannibal interview, Mikkelsen said Hannibal was Lucifer in human suit. Luo Yunxi actually pulled similar things in the early stage of the drama. There's something uncanny about Tantai Jin that you know he was not really human. Luo Yunxi was acting a character that was acting as human and there bound to be some flaws in the act. This flaws need to be brought on screen and this is not easy since they are not natural to the human actor. This demands a lot of restrains and layered performance.

An example of this is eps. 8. You wondered whether Tantai Jin was sad or not. His eyes showed a hint of sadness, but the expression was not really sad. Luo Yunxi must have put a lot of restrain during this scene. Other times, it was the opposite. The expression didn't reach the eyes.

The acting was pretty subtle. That's why when Tantai Jin showed his manic sides such as eps. 4, it's really memorable.