Unity is the greatest change to the Ubuntu desktop till date. You will able to get your hands on a completely new form of desktop, replete with features competing head on with other major operating systems. The UI is built upon Ubuntu’s netbook interface called UNE, and is quite similar to Gnome Shell but build on Compiz. However Unity, unlike Gnome3 and UNE, will be using the Compiz window manager instead of Mutter(which many users found to be slow and buggy). Also, many new and useful indicator applets are being developed which will help users add more functionality to a fresh installation. With Unity, Ubuntu 11.04 takes a completely new direction that will surely grab attention of desktop and netbook users alike.
Nautilus elementary will not be the default file browser. It was later rejected on the grounds that “patches were considered hacks”.
This will be the most significant change ever for Ubuntu.
I'm looking forward to this release... :D