I've used Virtuemart in the past with PayPal (something used by a few of you out there I'm sure) and I've always been inclined to appreciate such a robust e-commerce extension for Joomla. It's worked for me before, but in working with the latest version it has been problem after problem after problem. When I finally find a fix or a rough work around for one problem another one is encountered.
Don't use this if you're simply going to use PayPal there are too many flaws and very little relevant support in the forums. Other payment methods may be the same, but I assume that there's less interest in supporting PayPal since it is free and often viewed as a less than serious payment processor.
In any case, even if you get it to work there will be annoying little bugs to live with such as compiling all products as one during checkout or listing products separately but not transferring shipping costs. The biggest problem is failure to notify properly a confirmation of successful payment. This is the latest version and I never had this much trouble getting previous versions to work!