I've seen it in action at least once and I think it was a really good experience. Basically you could manage a single ecommerce profile and sellers could piggy-back on it and not have to set up their own payments system or even authentication. I think they may have put themselves in an awkward spot in between sellers and their customers data though. It's also a narrow niche in between fully-managed ecomm players like Shopify and fully custom platforms that big guys would be using.