You can opt to create a swipegood.com account instead of connecting via facebook.

I did see that, but the fact that facebook is even an option just put me off straight away.

Understandable. But frankly, if you've ever seen how banks operate their technical infrastructure you'd want to store all your money in a matress. I'm confident Facebook has much smarter people working to make sure their products are secure.

Most banks have ssl encrypted sites.

I think that's a bit unfair. Many large properties allow authentication through Facebook. I don't see why there is a concern with credit card information and Facebook authentication?

I like facebook log-in. No separate credentials to keep track of.