Took a couple of minutes to install and select the appropriate options, the instructions page is simple but covers everything needed (included an override to display zero values which I implemented first go) and when the client later wanted free shipping for selected items, John from GJC was as good as his word and responded within 12 hours (different time zones) with a solution.
Simple to install and easy to configure.
Just make sure that you download the correct version from the develop's website for your Joomla installation - his website is confusing, you gotta read the etxt closely, and I ended up downloading the wrong one, before I realised what was happening.
I have since used this plugin on a number of sites.
The fact that it also includes so many customisable options, like CSS control for the buttons, font types, themes and languages means that it's a no brainer. If you want your users to share your products (thereby increasing traffic to your site) then this is a 'must have'.
Remember, deep-linking (links back to specific pages within your site) are very valuable from Google's point of view. This plugin gave me the best way to share just the right info, and was easy to install.
One more thing... this is the second product I've bought from Giang from Joomdonation and his support is nothing short of excellent. Couldn't be happier.
Giang at Joomdonation/Ossolution, the plugin developer, was very helpful. Not only did he recommend an upgrade to Virtuemart 2 and assist me with that but he also helped me import the data.
I'd strongly recommend this plugin and especially the support provided.