I've used it for opioid/kratom withdrawal RLS.
It's surprisingly effective, but not a complete cure. It doesn't help you sleep, but it helps relax your muscles enough to at least lay still and not kick around.
The main issue with it in my experience is that tolerance develops extremely rapidly. It only seems effective for 2-3 days, then it stopped working entirely for me. Likewise, you should never take it for more than a week anyways, because it can cause it's own withdrawal apparently.
The first time I took it (160mg), it actually gave me a very pleasant, but light and short acting dopamine buzz. I never experienced that again, though.
But it does seem to help with RLS from opioid withdrawal, as RLS is known to be caused by low peripheral dopamine levels. It's the ONLY thing that actually helped with RLS for me.