A few times before I've tried using auto generated subs and every time I turned them off within a minute because so much of it is nonsense. Last time was about a month ago.
It seemed to get a lot of simple sentences right but every few it completely misparsed. Additionally, it seemed like every uncommon name or technical term became something else.
In light of your comment I went to YouTube to evaluate it again and... it's a lot better than I remember! I watched a few minutes of a video analysing some music and everything, including music terms, was correct.
The auto-generated subtitles still struggle with very strong regional accents, very poor sound quality or people talking over each other, but they're good enough for the vast majority of content. It doesn't seem to make dumb errors any more, just the kind of understandable errors you'd expect from a human stenographer.
Sometimes I try subtitles on something I cannot understand (because English is my second language) and that has not helped ever, it's always gibberish.
I tried going subtitles only a few times and gave up because I have to rewind and turn on sound every few seconds.
For Russian, which I don't understand, the result is maybe 50% intelligible (particularly when technical jargon is probably involved). But 50% is still infinitely better than what I can do with Russian myself (0%).