Their help page displays almost no fees (excepting ATM fee and account management).
However, their exchange rate earns them some % (I cannot tell exactly, it's somewhere between 1-3%, I didn't check for quite some time). And if your local currency is not EUR nor GBP you'll have to pay some extra fees (may be to cover forex, I don't know). Unless your local currency is USD, it's not worth having USD card since it has some more fees.