David Sparks on macsparky.com:
In my initial testing, Stage Manager feels like the best window management system Apple has ever put on the iPad and perhaps the most accessible window management system Apple has ever proposed on the Mac. The trick is holding everything to that one screen.
I don’t really miss multitasking on the iPad — nor do I have one that can run Stage Manager. But on the Mac — I’m continuously on the lookup, and Stage Manager looks workable.