From a customer perspective, it's one of the first times I've had a painless purchase experience whilst having NoScript enabled (and not having to greylist some random mirror of JQuery halfway through the procedure and lose all state). Everything seems to fall back to Plain Ol' Forms just fine.
So far, FastSpring has been amazing. Their web interface has always had everything I've looked for, and setting it all up has been easier than expected. Their customer service people are great too.
(If you already purchased and feel left out, send an email and we'll figure it out).