Unity is now the default user interface in the 11.04 Ubuntu Desktop Edition. Or at least it is if you have the right combination of video drivers and Compiz. Unity now uses Compiz 3-D compositing, not the abysmal Mutter framework of Ubuntu Netbook Editions up to 10.10. Which will be great when all the video driver issues are worked out. Right now, this Alpha release is so crippled by display problems, I won't be doing much testing...
I nearly gave up with this Alpha release because of the graphics driver issues. I ended up installing natively on two physical machines, plus a virtual machine and spending two days troubleshooting to get it working. The Unity/Compiz combo is really ahead of the drivers and I just about exhausted my patience and troublshooting skills to get 3-D on the Dell laptop. The worst thing is I don't know what I finally did the trick to get it working!
For now, it looks ok, performance is much better than Mutter. But it's Compiz so I expect nVidia drivers to crash.
The Pentium-4 has a decent nVidia graphics card and the display still doesn't work for longer than one boot! Unity won't run in the VM at all. If you don't have video drivers installed, you'll see the default two panel Gnome desktop layout.
Unity is only partially implemented. You get the Unity Launcher with the context menu replacing the Gnome top-panel. You can launch applications that are pinned to the launcher and switch between running applications. The context menu updates depending on which application has focus, all very Mac OS-X-like.
Anything running you can right click and pin-to-launcher. Unity has Quick lists on the context menu. You can now set it to auto-hide.
The workspace-switcher is now on Unity's launcher. You can drag windows from one workspace to another.
However, Application Places, the categorised menu display we're expecting, is not yet available in Alpha-1. Click the top-left Ubuntu logo and what you get is the unsorted applications directory. This is temporary, lets hope the developers can nail it tight before April. It does limit what you can test in this Alpha release.
The notification area is gone, replaced by the new Indicators. There's the new Network Indicator, with everything except the kitchen-sink on it.
The developers are touting a whole stack of responsiveness tweaks to make the thing faster and offset the complexity of the new features, such as indicators (network manager, sound applet, meMenu and so on).
Here we go with the first inclusion of Mozilla Firefox 4.0, Beta 7 web browser. All I'll say for now is it seems stable and is very fast
On the technical front
Ubuntu 11.04 Alpha 1 runs on Linux kernel 2.6.37 RC3, but the April release will have kernel 2.6.38.
The GNOME desktop environment is still version 2.32.1. No Gnome-3 now or for April, it's Unity all the way. RC