I have no doubt it will mature into a usable interface. However, after using it several times (my kids’ computer uses it), I want to pull my hair out every time I use it.
I was speaking about it to a friend yesterday. Maybe this analogy is a stretch but it’s a bit “modal” like vi. If you’re in “work mode” your windows are all that you see. If you switch to “activities” mode you can browse your open windows, your available apps, your workspaces etc. etc.
So like vi, you have to be conscious of which mode you are in and be ready to switch back and forth as the need arises. The benefit, seems to be reduced clutter. When you’re in work mode you don’t have to look past lots of icons, menus, panels and the like.