Ubuntu 12.04 LTS was release weeks ago, transforming Unity into a polished, fast and reliable interface, nevertheless, the new look&feel introduced various bugs, too.
Unity 5.12 has just landed in Ubuntu 12.04 as a stable release update, designed with fixing bugs in mind, as well a targeting (and achieving) a boost in speed.
The Unity panel's shadows feature now a faster, more pleasant look especially when users hover the mouse pointer over several indicator menus.