If you look at the previews of Windows 8, you'll see that Microsoft are making an even more radical overhaul of their DE. I wouldn't be surprised if some disgruntled MS Windows users switch to Unity or Gnome shell because both are closer than Windows 8 to a traditional desktop (!).

That being said, I myself prefer xfce, since it can be configured to suit my existing style of working. I'm very grateful it exists, since I'm not particularly attracted to KDE. But hey, freedom is surely what open-source software is about.

A few months ago, I used Gnome3 on 11.04 and I thought Gnome3 was kinda cool and edgy. When Ubuntu 11.10 came default with Unity, though, I realized I was sick of bloaty gui s, and I figured I'd look for something fast and stable. So I found Xfce (through Xubuntu).