I used it initially, had no major issues. And, yes, only wired connections for me. I then turned it off, since I saw that a lot of other users did experience issues, and also, because I don't really need or want it.

I then turned it on ONCE to use it to transfer files to another computer of mine.

BOOM!

The world of my main was completely reset. This on a very fast connection that I had no major issues with.

Thankfully (and I've been preaching this for decades) I had my backup and didn't lose much.

And yes, I had been EXTRA careful to click the right button when Steam asks you which save to use.