I tried it on a desktop PC, Chrome on Linux, Nvidia GPU several years old (seems to work well for most WebGL things though). I think what's missing from the current presentation is the "why". Why would I build something with it, and why would other people want to join in? I'm not saying there aren't good reasons, but the empty home page doesn't provide any, and nor did a few minutes playing around.
I think interoperability is what would really make a metaverse experience, so I'm pretty doubtful any single company could do it, even with Facebook's resources. I think the web itself is the closest thing to a metaverse we have, but it's still far away in terms of actual experience. I think that it's become universal because of the interoperability and common standards that mean it doesn't matter what software or hardware is used to create, interact with, or consume content, so it's a level playing field without one organisation controlling it, and so people are free to go nuts making stuff, without threat of losing it or losing access.