The interface works, I think it works well.
The only problem is, that it looks very 90sish as far the color scheme and looks like it should be some kind of Sesame Street website as far as the icons and colors are combined. I know this isn't a priority as far as functionality, but people that are testing the program will wonder why an effort hasn't been made to make the control panel more sleek and sophisticated looking. I remember looking at the other Cart programs and wondering why Shopsite felt so dated and whether or not that was a reflection of the functionality.
Shopsite.com was recently updated to look more sleek and professional...it is time for the interface to go through through the same revamping. I'm not being picky I just think it would help your bottom line and attract people that want to make great looking sites.
I remember first looking at the interface and thinking that management was going to think we shouldn't go with the software because if this people at Shopsite have made an dated interface perhaps this would limit our high ambitions.
They actually did think that and I had to convince them otherwise and we are all very happy with Shopsite now.