I was a bit sceptical, but I have to say that the horizontal workspaces work pretty well. Working with GNOME 40 is both efficient and aesthetically pleasing. And as a side note performance is much better too on Fedora 34.
AFAIK, most DEs place virtual desktops horizontally or in a grid, and I'm actually not aware of any other DEs that dynamically add new desktops as you use them rather than statically defining them up front.
Like on all the other desktops?