What is low VOC paint, and what is the durability like when compared with 'standard' oil or acrylic based paints?
Generally the durability is considered to be just as good as the older paints. The VOC-Free paints still have less color-selection (at least last time I looked), but that's been changing as demand increases.
The building I work in (in the U.S.) just completed a LEED-Platinum renovation, and used all VOC-Free or Low-VOC paints. Some of the special purpose paints were not available in VOC-free yet, but low-VOC paints covered most of what they needed (including paint for a metal roof).
I was impressed at how much less they smelled when I stood next to a painter with an open tray of paint for several minutes before realizing he had fresh-paint out (I was disappointed that it smelled like someone had painted a week before until I realized he was doing the touch-up painting right then). In the first year we haven't seen any issues related to durability.
VOC = Volatile Organic Chemicals.
Basically, it's the stuff that gives you that 'fresh paint' smell, but it also can cause problems for people with sensitivities even after you've aired out the painted room, as the paint will continue to out-gas.
There also exist 'VOC free' paints, not just 'low VOC'.
I can't comment on the durability specifically; it's possible that other aspects of the paint may be a more significant factor.