Also: Why would I use a payment service of the biggest copy cat company in the country? To deliver them my revenue numbers on a silver plate so they can decide if they should "enter my market"?
They don't even openly publish the upcoming fees and just want you to "vendor lock-in" (or dig around to find the transaction fees somewhere hidden on their site). really sad :(
As an European I can tell you that no one is going to wait years for a valley startup to establish itself in Europe when there are sufficiently good alternatives right here and now.
The APIs are REST. You don't need a client library.
But this comment is down voted while it conveys a valid point. Please take a step back and try to take view this from a European (non UK) standpoint.
Are we reading the same thing?
What I'd like to know is which consumers are supported, and what's the experience like, e.g. for American consumers paying through this.