The system works if you want to downgrade to Joomla! 2.5.
Yes at begin we concentrated on fixing bugs. Since the relaunch we have new virutemart 2 documentation http://docs.virtuemart.net/
The requirements are written down here http://virtuemart.net/downloads . VM2 has the same requirements as joomla 2.5. The experience with j1.6 and j1.7 tells us that we wait with joomla 3.x compatibility for the next LTS 3.5. Expect that we will be ready in time.