From a retailers perspective, a feedback page would be a great addition.
I know at first glance, it seems similar in a way to writing a product review but a product review is quite specifically about an individual product - feedback would allow a customer to comment about their general shopping experience ie how quickly the item was dispatched, how it was received etc, how satisied they were.
i visualize a link on the infoblock. Feedback comments would be limited to a certain amount of characters with edit/delete function enabled in admin