I only wish they had payment information posted somewhere. Just a little "we accept" blurb would have been enough for me. I couldn't find anything, which I thought was unusual for an online store. Perhaps Sony and Apple do not post it either -- I don't know -- but I have a GC for iTunes and I opened a Sony card to buy my Reader, so I didn't think twice about how I was going to pay to either one.
I didn't want to sign up and order a book and find out the bill would be mailed to me or something. It is one thing to assume they take Visa or Paypal or whatever, but it's nicer to have that spelled out for me.
This also probably means I'll need to set up an account before I try to buy a book through the app, to make things simpler.