A year after the release of Ubuntu 11.04, Natty Narwhal, the LTS release of Ubuntu, Precise Pangolin, was released. The new version featured Unity 5 with features such as the HUD and lenses. Also on the list of additions was the inclusion of classic gnome and the replacement of banshee with good-old rhythmbox.
A page out of Debian's book
Debian, the father distribution of hundreds of derivatives, uses Gnome 2 in their stable version. After all the gripe over Gnome 3 and Unity the ubuntu development team decided to include a full blown gnome-classic DE in the release. The inclusion was aimed to move people away from outdated versions of Ubuntu that are still clinging to gnome 2.
Rhythmbox, Debian's media player of choice, is also included over banshee in this distribution. After dropping rhythmbox to include Banshee for 11.04 they have gone back to their roots, leaving banshee in the dust. This was because of community preference, bugs in banshee, and stability in Rhythmbox.
Despite the reasons for these changes, Debian users will be in a more comfortable default environment than before when switching to Ubuntu.
In contrast to the original Unity from 12.04 Unity 5 is a vast, vast improvement. With one fell swoop the Ubuntu team has turned Unity into a tool of timesaving and productivity, and it's called the HUD. The HUD, activated with the alt key, allows access to the menu bar of any application. It also caches results so it can learn your preferences, making quick judgments about what you want to do and what you want to do quickest. The Unity interface can now be customized in a ton of ways, from myunity to the ccsm to even the appearance menu.
Small improvements define the latest version of Unity, however. The simplest features like leaving old queries in the Dash really make using the interface a much more productive experience than before. Unity is no longer the clown car of the desktop interface world.
12.04 is the first distribution after a year of volatility over some of Canonical's decisions to get things right. They dropped unstable software in favor of old, stable software and pushed enough bug patches to make Unity look like a family quilt. Where 11.04 had a cutting-edge, unstable feeling to it 12.04 is a noticeably stable experience that is easy for newcomers and power users alike.