I recently had a major issue with my X server because I tried to get the 'big desktop' working by installing newer proprietary drivers for my video card (ATI Radeon Xpress 200m) - gdm refused to show up. As a result, and because I needed to get down to work on an overdue midterm paper, I decided that the spare space on my harddrive could easily use an install of the upcoming Intrepid Ibex (to be released on Oct 30th 2008).
I installed regular ubuntu because I needed something as guaranteed to work as soon as possible (installer & all) to get my paper draft up and running. But now that it's installed, I'm installing components of the UbuntuStudio suite as I go (the realtime .27 kernel isn't ready right now, so I've yet to really attack audio testing). This - if it remains stable - may just turn into my Ibex install, so I'm beginning to make myself at home, custom icon set and all.
So far it is quite a nice looking system. Compiz works out of the box (no proprietary driver needed for my - previously fglrx driven - card) and even comes with a few new effects (a cylindrical & spherical desktop cube, etc..). The UbuntuStudio gtk theme has nice looking blue circles as the minimize, maximize, close buttons; nicely shaded buttons; crisp lines; and a rounder looking edge to everything. The only thing that made me want to hurl was the default Ubuntu wallpaper and login screen - ugh!
The 2.6.27 kernel is quite fast, from my informal perceptions, but I'm curious to see if this new responsiveness carries through to the RT kernel once its released. There are also the slew of newer verions of most programs (Gimp 2.6, Ardour 2.5, Kino 1.3, etc...). Beyond that, there are a few basic changes to the logout menu, wireless network manager, and other meaningless items that some UI designer wanted to spend some time on.
The official writeups for Ibex talk about many improvements for laptop users, including the new Network Manager 0.7, an encrypted private directory inside your home, and a guest login option. There's also a totem plugin for BBC content that you can easily activate in totem's plugin menu.
Overall, despite the troubles the dev team has expressed over the .27-rt kernel, I think this release is a nice improvement that does Ubuntu proud and that I'm very happy running.