I use it for my music files and audio books as it is smaller than mp3. In average it was around 1/3 less space used, I think. I do not hear a difference, but just to make sure I usually convert from the highest available format available, often FLAC, to opus using ffmpegs default settings. No regrets so far. Doing this for a few years now.
[EDIT] For downvoters - I didn't mean they took the Anthropic's product name. Time direction doesn't allow that.