I think the difference would be its lower transaction fees than to its competitors, as stated on their FAQ. "In the future when we begin charging fees we will give all users at least 30 days notice. Our fees will be in-line with our vision to provide a cost effective solution for Merchants."
Lower fees are declared as the main advantage though no concrete figures are disclosed. Looks shady
I don't blame you for being doubtful since we do need to be careful with our money. IMO, I think they might be legit and will be proven in a few weeks to months from reviews.. It would indeed be awesome if they pull this off.