Ubuntu Unity is a desktop experience designed for efficiency of space and interaction. It maximizes usability and minimizes complexity. Everything is available just 1 click away and almost everyone enjoys working with it. But the problem is, you cant get Unity working everytime on your computer because it needs 3D effects enabled by-default.
After Canonical announced they are building their own display manager to replace X and to squash the Ubuntu dreams of Wayland fans, they also announced Unity Next, a new session-level shell implementation build on Qt and QML. When Unity was first introduced back in 2010, people didn't like it.
Ubuntu 12.04 comes with Unity, by default, based on Gnome 3.*, new features in Unity interface such as HUD seems to be cool but many people still doesn’t like Unity. Gnome Shell Interface is another great option for them. Since, both the interfaces are built on the top of Gnome 3.* – they have no compatibility problem at all.
Unity is the default desktop in Ubuntu 11.10 (current stable version) or 12.04 LTS (upcoming, although beta 1 has released), so if you’re a new Ubuntu users and want to tweak some default settings (e.g fonts, icons, themes, behavior, launcher etc) of Unity Desktop, then try the Application called – MyUnity, very similar to what Gnome Tweak Tool does for Gnome Shell interface.
According to the latest "ubuntu-meta" package update from the Ubuntu Quantal Quetzal repositories, Unity 2D will no longer be installed by default in Ubuntu 12.10, and Unity 2D users are being transitioned to the Unity 3D session, just like it was discussed at UDS-Q.
I installed Ubuntu 12.10 on my notebook. During install there was no question if I would like to have full accelerated Unity 3D or using low graphics LLVMpipe, Ubuntu install does this by itself. How can I check which one is actually applied in my case?