http://www.h-online.com/imgs/43/6/5/2/4/6/2/gnome3logo-79adaf5c99050221.png
After around five years of planning and development, the GNOME developers have released the third generation of their Linux and Unix desktop, GNOME 3. GNOME 3 brings new operating concepts and a new look; the GNOME Shell reduces the visual complexity of the user interface to allow users to better focus on the applications that they use. Virtual desktops are also now an integral part of how users work with GNOME, with simple workspace navigation and a single keypress (or mouse gesture) able to bring an overview of all the windows and workspaces.
http://www.h-online.com/imgs/43/6/5/2/4/6/2/aee8228b414fe56c.png
The GNOME developers have also, as is traditional, reduced the number of configuration options; the changes usually help users who are new to the desktop work with it but also usually run into strong criticism from experienced GNOME users. In general, GNOME 2 users will need to retrain themselves for the new environment of GNOME 3.
For more information about the changes in GNOME 3 and how to adapt to them see The H feature “First Look:GNOME 3.0”.
[Source]