I picked this up, so users could redeem free codes from our website. Unfortunately, when posting items for "free", you can't collect any data. The only thing you can ask the user for is an email address.
More-over, when pricing is set as a minimum price, the default price box is blank. Any pay-what-you-like system these days has it prepopulated (at least with the minimum value).
That all said, it is working so far for me, but I worry about the long term support and the limited feature set that this has. There is a reason you can't install this through WordPress, and thats because it is feature limited, and you probably won't purchase it.