After the release of Unity, Ubuntu isn’t well know for the Gnome support. That made it an unpleasant distribution for lot of people. However Ubuntu 12.04 is more Gnome-friendly that the earlier releases (11.04, 11.10, 12.04).
What’s more cool is that in Millbank Tower, London (Canonical’s headquarters) they think to release an Ubuntu Gnome Spin with the upstream Gnome. Until then you can add the GNOME3 Team PPA and get a better Gnome experience.
To install the repository run:
sudo add-apt-repository ppa:gnome3-team/gnome3
sudo apt-get upgrade
If you want a totally crazy experience with Gnome 3.5.2 Alpha you can also install Ricotz repository.
sudo add-apt-repository ppa:ricotz/testing
sudo apt-get upgrade
GNOME3 Team PPA is considered stable and you can safely try it but Ricotz PPA will likely brake your system. So if you don’t know how to revert the changes with ppa-purge is better to don’t try it. Also you cannot install at the same time both PPAs, just pick one :)
Before you install these repositories you MUST read PPAs info
*Note Even with these PPA’s you won’t have a 100% Gnome experience because Ubuntu insists to don’t ship some technologies that are Gnome3 requirements like systemd. Distros that are well known for Gnome 3 support and are easily to set up, are : Fedora, Mageia, openSUSE.