http://www.wired.co.uk/magazine/archive/2012/04/features/ins...
So, proceed with caution if you decide to use them. (That being said, I wonder if Stripe will just buy them in order to get European payments working?)
Additionally, I don't know if I can criticise their model. Yes, it's not very innovative, but on the other hand you can think of it as a outsourced European development team for US-based startups. They know the market, the language(s), the problems. They do the development work and then if the original startup wants to buy the product, they can. Who knows, perhaps it might even end up being not much more expensive than setting up the infrastructure and acquiring the knowledge required to operate in the EU. It might also serve as a test case: "is service X really going to work in the EU?". They take the risk that something might not work.
As an EU-based developer (who never used any of their products. yet?), I also think it's valuable for us (EU-based developers). Instead of waiting for startup X to get their act together, they offer us an alternative, which then later might be merged with the original product.
As a side note, there is a bit of a unintentional Schadenfreude to be found in this article as well. Since it's 6 - 7 months old, their investments in Facebook, Zynga and Groupon doesn't look so hot anymore as it did back then. Maybe they should avoid the investment side of things.
Edit: grammar
This is important to keep in mind if your company uses them to accept payments.
Also, I think it's a bit unfair to reduce the brothers to a "copy-cat" title. This happens everywhere, its just that they are the most successful at it. There are a lot of really cool tech companies in the valley that are relevant to non-english-speaking countries and developing ones but these countries don't fully benefit because the originators of the ideas pay no special attention to this countries. Mere providing different language translations does not breakdown the different albeit subtle differences between different cultures.
I think the samwers should be commended for what they do especially for their German market.
Stripe would never, ever, ever acquire a clone like this. First, because the notion is already rare. But more overwhelming is Stripe's intense focus on creating its own culture and building its own stuff.