I have been using this extension for years. I didn't like Virtuemart 1.x too much. But with 2.x version, I am satisfied! It is free (like always), payment plugins in 2.x are so easy to integrate and developed. The code structure is now simple and easy to customize. These things make my projects more easier to finish and my clinets are so happy!
If you want to build a shopping site. I recommend Joomla and Virtuemart!