I will evaluate and write this review with the standard ratings of MDL, in additional I will add production/cinematography/directing next to those as a factor.
Out of all C-dramas I have watched especially fantasy ones, I'd say it has done the best with planning and the use of budget.

Production/cinematography/directing: amazing job
I think it's probably one of the best aspects of the drama to me. The drama was not one of those with the HIGHEST budgets as a webdrama, but used it's money pretty well imo. Like most time I have problems with the shabby CGI in Chinese dramas. But The Untamed knows how to limit it and when it's using it then it's pretty decent. For the cinematography, all places and background sceneries are all wisely chosen.

Story: decent script writing + changes and differences with the original work
The reason why the story is outstanding is probably thanks to the original novel and the scriptwriter doing a decent job. I have to say the changes made for the part of changing/leaving out the romantic love between the male protagonists actually made the drama more different and more outstanding to me. You could focus more on the criticism of clear fake separation of good and evil and also societal pressure (IMO). I personally preferred the original story telling with the time jumps in the novel, which keeps more curiosity and expectations alive. But in general I can understand this decision might be coming from being afraid that the viewer would getting too confused with all those jumps.
What I didn't like that much was probably the end ark, I felt compared to the rest of the drama, it was a little bit draggy and I felt they could invested the time in the previous episodes more instead. Besides of that there are some few changes I didn't like or preferred to have not done. But those are still pretty OK to me.
All in all I think out of all Chinese dramas I have watched, The Untamed actually has the best story and script writing despite some changes.

Acting/Cast: competent idol cast with amazing lead
I think all the cast were chosen well and they doing a pretty decent job especially if you consider actually nearly all actors are having an idol background. But I never felt some BAD acting. The best choice I have to say is actually Xiaozhan as Weiwuxian. He was literally bringing the character alive and being able to do a great job either playing as the playful troublemaker or vengeful dark avenger completely. Despite never having received acting lessons and coming as an idol. So I'm not surprised that he roses to fame still with that big amount of potential.

Music: Best C-drama BGM to me.
All melodies are suiting the scenes and backgrounds. And the Qin and flutes are all well placed. Nothing much to say just perfect OST.

Rewatch Value: very high
Due that there are so many different medias for this work like novel, audio drama, manga, animation and audio book, I think it's actually pretty worth to rewatch this drama and compare the differences. The view might have changes or the viewer might being able to look deeper into the story than before and discovering other differences/changes.

Overall: One of the best C-dramas I have watched with a good cast, amazing male lead, great cinematography, perfect BGM and deep story. Definitely worth having a try at least.