Used it to purchase Airtran tickets to Atlanta. Works exactly like a credit card account without having a "physical card". Lots of merchants used it handle their online purchases. I like the fact that I don't have to worry about a card being compromised. APRs were comparable then I don't know where they are now. When you make a purchase you enter your user name and a two other items which should be known only by you.
Worked fine for me. Haven't used it since for airfare.