Looks to just be a button that sends you to PayPal, which is what we utilized before. We're interested in having the entire form on our site, without leaving and actually going to PayPal. Just a one-stop form to do it all.
If that isn't possible, we'd at least like the entire form, short of the final payment info, be on our site. A good example would be how Ubercart works with Drupal e-commerce. You fill out the entire form on the person's site, click "finish checkout," and it temporarily sends you to PayPal just to do the credit card info. After that you're sent back to the original site with a success message.