It worked great in NXT. Not as much on RAW/Smackdown.
It's a cool look, and I think they're using it good right now. The point of it has been Balor gets pushed to the point where he almost snaps and turns into the Demon. Before he took a hiatus (eventually going back to NXT) it was just random announced appearances for The Demon, which felt forced. Ironically the thing that did The Demon in was his match with AJ Styles, which was a replacement match. Balor had no reason to Demon for the match but did it anyway because it was announced.