UI wise it'd be nice to click an area of the PDF and be prompted for the kind of input I wish to create on that spot, but I survived.
Admin wise it'd be nice to be able to say "and don't allow them to click OK without having placed at least X signatures".
I pitched this to our IT team and our HIPAA compliance team. Their issue was they don't want NDAs and similar things they sign in the cloud. "If they would open source this or sell us a self hosted version, we'd use it and it'd be better than what we do today."
It'd be nice to be able to get an identifier in the subject line that'd let me parse out documents received back from people by person. I can see how sending this out to 60 people would become unwieldy. Perhaps that's how you "get em" - you allow this for free but you have to create an account to organize all you've sent.
The number of companies who send me a doc file to enter my cc info in and send back to them is endemic. If I as a business owner and credit card holder could turn it into a PDF, use this service to fill it out and securely send it back, it'd be good. I suspect this isn't the killer use case, but I mention it.
This is a legit and useful idea. Have an upvote.