Not the OP, but I appreciated its attempts to declutter and rethink the layout. It encourages a full screen, minimalist style, and jumping between workspaces for different task sets. Hovering and slide out menus rather than permanent bars (although those are still an option). It also brought in some features like Split View before they hit mainline Firefox releases.

Unfortunately, I found it had some unfortunate video playback bugs for me on Linux, so I ended up bouncing back to Firefox. I'm also bit leery of relying on smaller projects with all the supply chain issues these days...