I attended a talk today from some of the developers on the GNOME Shell project. I have to say, the stuff they’re doing is pretty visually impressive. They seemed to have some pretty solid design ideas from a UX perspective. And watching how easy it was to add extensions was really cool.
It’s (unofficially?) part of their design doc to make GNOME Shell “f***ing amazing”, and I think they’re doing a good job of getting there.
There are some things I don’t like about it, though. They moved the level at which you can configure the system by swapping modules. They make it really easy to create (somewhat) superficial effects by creating modules, or changing the source. But they took some of the things that are modules in GNOME 2.x and baked them into the GNOME Shell architecture. In particular, they made metacity (the window manager) an integral part of their architecture. So no, it does not look like GNOME Shell will ever support other window managers. Which sucks, because right now I use xmonad with GNOME, which I like a lot.
I suppose it doesn’t really matter, though. A lot of the work that they’re doing in GNOME shell is to make workspace and window management more intuitive for nontechnical, casual, users. So I’m guessing that if you’re technically inclined enough to switch out your window manager, then you’re not going to need most of the functionality in GNOME Shell.