It is better to have feedback after order completion where the client rates the shop, and the shop seller also rates the client. As in ebay. This review should be separate from product reviews. Product reviews are about the product and not the shop, it could be that the product is not made by the shop so the reviews reflects the comments of users on the product itself. But shop reviews reflect the clients comments on dealing with the seller and his behavior and performance and answering question, etc.