When we started with them, they had an excellent customer service team. They helped me through set-up and answered questions promptly. Their order process was confusing however, for both buyer and seller, and their graphic interface was antiquated and boring.
Purchases from the site were run through them. That is the buyer would pay Gemm, and Gemm would pay the seller less a commission rate. Payments were made after reaching a certain threshold. In the end, we are out a bit, but I am more concerned about their employees, whom I wish the best of luck.