hi Michael,

upgrading from 2.1 to 2.2 in admin panel hovering the red baloon is visible a description about what change in latest release.
In the 2.2 version there are no particular new features, mainly improved caching system, better compatibility for new menu types on Joomla 3 and source code optimization.

We are now developing version 2.3 that will add some new features, mainly to improve scalability of component for example to generate very large image sitemap also with low server timeout.