Cinnamon is a Gnome-Shell desktop fork. It is not strictly a Gnome-2 interface, although the developers aims are laudable - to produce a simpler more traditional desktop interface.

Development seems to be rapid. It is usable and certainly fun to play with with a growing number of extensions to install to extend the base installation.

How to install

for 13.04 & 13.10, 14.10 & later

Cinnamon is now available in the Universe repository

cinnamon

Alternatively - from the command-line:

sudo apt-get install cinnamon-desktop-environment

Since it is in this repository, it is community maintained and thus it is up to the community to update the packages as and when new releases and bug-fixes are released.

For Ubuntu 14.04, there is currently no cinnamon packages in the Universe repository.

Via PPA for 11.10 and later

EDIT: 22/05/2014 - the PPA ppa:gwendal-lebihan-dev/cinnamon-stable has been removed or hidden from public view. I contacted the maintainer and the following is their reply:

The stable PPA is indeed no longer being maintained.

The nightly PPA is being kept for development purposes and should not be used on any sort of production machine (it can and will break at any time).

To be honest, I don't have an alternative to offer Ubuntu users at the moment, apart from switching to a distribution that does support Cinnamon. There are many such distributions out there, and I'm only hoping for someone to (finally) step up on Ubuntu's side to provide proper packages to its users.

EDIT: 25/04/14 - Two alternative PPA's have now been created - both claiming to enable the stable version of Cinnamon for Ubuntu users. I cannot vouch for the veracity of these PPAs

Option 1: 12.04 & 14.04 users only:

sudo add-apt-repository ppa:tsvetko.tsvetkov/cinnamon
sudo apt-get update
sudo apt-get install cinnamon

Option 2: 14.04 users only:

sudo add-apt-repository ppa:lestcape/cinnamon
sudo apt-get update
sudo apt-get install cinnamon

As an alternative you may wish to consider the unstable nightly automatic builds - please note Gwendal's warning above:

sudo add-apt-repository ppa:gwendal-lebihan-dev/cinnamon-nightly
sudo apt-get update
sudo apt-get install cinnamon

Option 3: In addition, you can also install cinnamon 2.2 in Ubuntu 14.04 LTS and derivatives by adding Linux Mint 17 Qiana repository in your system.

Open file /etc/apt/sources.list with nano command:

sudo nano /etc/apt/sources.list

Add the following line at the end of file /etc/apt/sources.list

deb http://packages.linuxmint.com/ qiana main upstream import

Update the repository then install the authentication key

sudo apt-get update
sudo apt-get install linuxmint-keyring

Update the repository again and install Cinnamon 2.2:

sudo apt-get update
sudo apt-get install cinnamon

After installation

Logout and select the Cinnamon session:

Enter you password and you'll see the Cinnamon desktop

... showing the traditional start type menu and applet design from Gnome-2

Extensions/Applets

The Cinnamon desktop uses the same philosophy as Gnome-Shell - functionality can be added to by installing Extensions & Applets.

Cinnamon uses its own Settings tool.

Cinnamon Settings

Cinnamon Applets

Similar to gnome-shell extensions - you can install applets from a dedicated Mint website.

I encountered this problem when upgrading from 12.10 to 13.04. No matter what I did, the VMware Tools installer couldn't seem to find the headers. For the record, here's how I installed the headers:

sudo apt-get update && sudo apt-get install build-essential linux-headers-$(uname -r)

Turns out, the installer is looking for the version.h file in under [kernelsource path]/include/linux/version.h, it's not there. The location of version.h is [kernelsource path]include/generated/uapi/linux/version.h

The solution is a symlink:

sudo ln -s /usr/src/linux-headers-$(uname -r)/include/generated/uapi/linux/version.h /usr/src/linux-headers-$(uname -r)/include/linux/version.h

After creating this symlink, I was able to run the VMware Tools installer without a problem.