Beginning with 11.10, Ubuntu no longer ships with the old Gnome 2 “Classic Desktop“, but you can easily install it (or at least the Gnome 3 version) if you prefer it to the default environment, Unity. While Gnome has evolved to version 3 and its sleek and flashy Gnome Shell, the minimalist Classic desktop is still available as the “Fallback Mode“. Or you may be dying to try Gnome Shell, as it certainly gives Unity a run for its money, and the rapid development of extensions makes it better with each passing day.
Check out this guide on how to install Gnome Classic and/or Shell, log out once installed, open the login menu (should be an icon near your name, currently a gear), and choose either:

♣ GNOME: “Gnome Shell”
♣ GNOME Classic: The Gnome 3 version of the “Classic Desktop”
♣ GNOME Classic (No Effects): “Classic” for older PCs & video card issues
♣ Ubuntu: The default “Unity” environment
♣ Ubuntu 2D: “Unity” desktop for older PCs & video card issues
It’s as simple as that! You can now enjoy your new preferred desktop environment, or have fun jumping between them. And don’t forget, you easily can install many more desktop environments, like Kubuntu‘s KDE, and log in between them at will.
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Related tip (Gnome 2 Only): Ubuntu 11.04 Classic Desktop: How to Log Into The Old Gnome Environment Instead of Unity
cool tried it out and it worked wonderful and am new to Ubuntu and the only version that could work with my computer without any problems was the 11.10 version, and i kinda got to like it, but had a little problem causse i wanted to enjoy the classic desktop and with this i was able to get a taste though just for a few minutes but it still felt gud
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Yes, it’s good to have a choice. So you can still log into Unity any time you want, as well as install other desktop environments (sudo apt-get install kubuntu-desktop if you’d like to try KDE!). Cheers.