Linus Torvalds in a few days ago on Google + said that GNOME 3 "no tolerance of clutter", change to the XFCE desktop environment. Here's a little comparison of Gnome, KDE, Xfce, and LXDE. Finally comes down, no good or bad, suitable for their own is the best, the user experience is the best, is the mature successful product
GNOME 2.x
GNOME 2.x is known as the traditional interface, the default 2 panels. In terms of system resource usage, GNOME 2.x requires less RAM and higher CPU than GNOME 3. In both respects:
XFCE, LXDE < GNOME 2.x
In the current release, the LInux Mint,debian still uses GNOME 2.x as the default desktop environment.
Recommended System Requirements for GNOME 2.x
Required RAM
384 MB
Required CPU
-MHz
http://linuxreviews.org/software/desktops/
GNOME 3
Gnome 3 is a new version of GNOME that is significantly more transformative than GNOME 2.x. Gnome 3 is relatively intuitive, and most students are accustomed to the traditional GNOME 2.x desktop environment. GNOME 3 has only one top panel, and the traditional menu is gone. Click "Activities" in the top left corner to view apps, work partitions, and more.
Currently, the release version of Fedora 15 uses Gnome 3 as the default desktop environment.
Recommended System Requirements for GNOME 3
Required RAM
768 MB
Required CPU
-MHz
Http://fedoraproject.org/en/get-fedora
Unity
Unity was originally designed for netbooks by canonical and was first adopted as the default desktop for Ubuntu 11.04. Unity is more resource-intensive than GNOME 3 or KDE. In the Unity desktop environment, there is only one top panel, and on the left side of the desktop there is a class of app launcher for the dock.
Recommended System Requirements for Unity
Required RAM
1 GB
Required CPU
1 GHz
Http://askubuntu.com/questions/22402/will-ubuntu-11-04-work-on-my-old-pc
Kde
KDE has the class Start menu for Windows. The interface is gorgeous.
Many distributions, such as openSUSE, PCLinuxOS and Mandriva, use KDE as the default desktop environment.
Recommended System Requirements for KDE
Required RAM
615 MB
Required CPU
1 GHz
Http://itmanagement.earthweb.com/osrc/article.php/3930006/GNOME-vs-KDE-The-Latest-Round.htm
XFCE
Fewer resources than GNOME, KDE. Suitable for old machines, lightweight desktops. Similar to the Windows interface environment. Many students who are not accustomed to gnome 3, Unity's new desktop, many have opted for Xfce 4.8, including Linus, a great god classmate.
Recommended System Requirements for XFCE
Required RAM
192 MB
Required CPU
MHz
Http://wiki.xfce.org/minimum_requirements
LXDE
LXDE is also ranked among the four desktop environment, lightweight desktop, less resources, suitable for old machines, not to mention the new high-profile performance on the machine.
Recommended System Requirements for LXDE
Required RAM
MB
Required CPU
266 MHz
Http://lxde.sourceforge.net/about.html
Of course, other window managers such as E Fluxbox, OpenBox, Enlightenment, ICEWM, and JWM are also super-resource-saving options.
Overall Rating:
The following is the original author's assessment of the Personal Desktop Environment/window manager.
Linux Desktop Environment Gnome,kde,xfce,lxde usage comparison (RPM)