It took days to integrate into an existing Joomla2.5 site and I found that I had to hack into the code to style most steps of the purchasing process. Integrating Paypal was complicated, even with a 3rd party plug-in. Impossible to edit email templates for invoices without advanced PHP knowledge.
Overall, yes it functions as an ecommerce platform and probably has some nice advanced features, although many of these are only available as paid-for extensions - but I found the overall feel to be flimsy and not user-friendly. In future I will pay for commercial platforms and recoup the cost from the development time saved in setting up.