During the last couple of years, I've created a few Joomla websites with Virtuemart as the e-commerce component. Although I struggled a bit to start with, I think it works fine now. I still find the control panels quite cluttered and not exactly intuitive, though. It took a lot of time to get to know all the quirks and oddities (like links that lead to not-yet implemented features...!). After a while, however, I have come to like VirtueMart, and have managed to set up a few quite successful webshops using it.
One of the things I don't like so much is the lack of themes and templates made for Virtuemart. A few weeks ago I was made aware of Yagendoo, a company specializing in templates and extensions for Joomla.