Although at at present I only have one install of SunShop, my clients and I are very happy with the product. It was easy to install and configure. My client particularly likes the backend with regards to reports on customers and items sold. They also appreciate that there is an iPhone app that they can use to stay on top of things in their store, even when they are not in the office.
As the designer, I also found the interface for connecting PayPal, UPS and FedEX to be straightforward.