When I open Settings - Appearance, there are two problems:
I selected color (non-wallpaper) background, and is shown as current background. However, the desktop background does not change.
There is no Launcher Icon size slider in the bottom.
I see this in 12.04 64 bit Unity, running under VirtualBox. The same "parent" Ubuntu works as expected.
Solved by enabling 2D and 3D acceleration in VirtualBox settings, which allowed Ubuntu to run in 3D mode.