I say this very respectfully, I love nopCommerce, from programmers point of view is a dream product.
I would like to suggest that adding products be made a simpler process.
this issue became apparent after one of my customers spend some 4 days filling her store with products, but then went to another service (http://www.ocnk.biz/) and was able to create the same store in a day.
her biggest complaint with nopCommerce was the fact that she had to click, save, and navigate to several pages to add a single product, while "my competitor" only required one page, one save click and done.
As a programmer, I can enumerate hundredsof reasons why my services, and NopCommerce are a better product, however is hard argue when something "can be done" in one day versus 4.
I want to reiterate that this is a humble suggestion, I almost feel bad saying it because, nopCommerce is such a great product, which I like very much
