I've been playing a bit with Gnome 3, both inside VirtualBox and on my prior laptop. As I mentioned before, while it's kind of slick, it's also not a very good interface for power users. It feels more like an experiment on "how might people have dealt with their computers had a different desktop paradigm won?" than a sequel to the highly-usable Gnome 2.x. The loss of the iconify/minimise button is pretty serious brain-damage.
I am highly frustrated that Gnome 3 components no longer play nice with other window managers (I've used WindowMaker for years, and am not in a hurry to switch).
Ubuntu 11.04 ships with a desktop environment called Unity (contrast to Gnome 3's Gnome-Shell). On first glance, Unity is not very different from Gnome-shell; both make it slightly hard to get to the filesystem, both have a fairly sophisticated app browser, and both use 3d effects. Both are also very pretty. However, Ubuntu's Unity at least lacks the brain-damage of removing the minimise/maximise buttons.
I continue to be deeply impressed at how polished Ubuntu is. In the virtual machine I put 11.04 on, they've even customised WindowMaker (I haven't made much use of WindowMaker themes because I used NeXTStep and am used to how it looked) to have a lighter, less boxy look-and-feel. Their installer is much slicker, and everything felt like it had a lot more thought put into it. The only thing I still really dislike about Ubuntu (for desktop use, anyhow) is the package system; if they had an RPM/Yum based distro, I'd be using it on my personal (non-server-type) systems (and maybe move to FreeBSD or CentOS).
That said, I think the move away from X11 to Wayland is among the worst ideas imaginable for a Linux vendor, and should be protested as strongly as possible. Canonical deserves nothing but condemnation for that (likewise with anyone else considering moving with them).