Looking at the capabilities, this plugin really is a great e-commerce plugin. However, this plugin is made to FORCE you to buy their themes.
Theming this by oneself is impossible. You are forced to have their pages, and also the widgets don't appear on normal wp pages, just on the their pages.
So you can't have pages that display products from certain categories and add widgets where you want, thereby making a custom site. You have to use THEIR pages (why would they even do this?), and it is their way or the high way.
As I said, this plugin is made to force you to buy their themes.
Why not just have a free version with limited capabilities and a paid one with extended capabilities and allow people to make custom sites damn it?