We know that there is a big push for J2.5. Everyone wants to upgrade. But, its just not ready yet. J2.5 will need some time to get the bugs out of it and get it so it is working perfectly. Developers need time to upgrade the components, modules and plugins so they are compatible.And virtuemart needs time for J2.5 to become stable before they can complete their upgrade . VM2.0 for J1.7 is not even working perfectly yet.
I found some interesting posts about the issues with upgrading VM2.0 so it can work with J2.5.
We are not making this up, it just is not working yet. If your J1.5.x website is working fine with VM1.1.x, stay with it. For now the only thing you will gain with upgrading is headaches.
Please read the following Virtuemart forum posts on Joomla 2.5 and VM 2.0 issues
At some point everything will be stabilized and working, but please expect months for this to happen.
UPDATED: July2. well its gotten a lot better, and as we have release payment and shipping plugins at joomlacache.com, that has helped a lot. We are complete experts in virtuemart 2.0 now and have accomplished many customizations. VM2.0 works now, but with a lot of work debugging and fixing. We have accomplished miracles, so dont hesitate to ask us to help with virtuemart 2.0.