I can understand the last few reviews, at first glance this can seem very daunting, however I have found if I stick to a tried and tested install approach it works fine. Install Joomla, install Virtuemart, install sh404sef (if needed), now do all your set up and make sure it all works. Be aware that there is a direct relationship between the Joomla global settings and the VM settings, and to get postage to work you need to make sure it is active in the path to purchase, these being the two most common issues. It also helps if you install the demo data as this will illustrate the settings very well. Having set it all up, back it up! Then you can add in all the other eye candy etc that you want on your site safe in the knowledge that if you mess up your install you can roll back to a good version.
My thanks to the developers and others in the community for their help in the past.