A cultivation story with BL sub hints. Mo dao Zhu Shi was one of the first chinese series to receive a decent amount of attention in the west. This was because of its good animation but also the characters.
The story itself is built around the characters and thats why the characters for me have a greater appeal. A lot of the story is flashbacks to built specific relationships between characters as well as developed the history and motivations of each characters that we get to know first in the present.
This creates interesting characters and gives a back drop to relationships in the present between characters and it is exactly these relationships that are the focus of the series and where it excels at. Its a good show overall, no wonder it garnered attention in Japan with a dubbed version earlier this year.