This organic store is relatively big and, like the two other ones in Rennes, offers numerous vegetarian/vegan products, from vegetables and fruits to cereals and faux-meat. It's a really practical shop in France. And they have a vegetarian restaurant, which is quite unique in France for such a shop!
However, I find that prices (of the shop) are high and that they do not always privilege local and seasonnal vegetables. They also have a butchery inside and the Biocoop network does not support vegetarianism and veganism (read their magazine : http://www.biocoop.fr/content/download/8244/94348/version/2/file/CA63_dossier_leger.pdf).
Cons: has a butchery inside, Biocoop does not support veganism, pricey