The Crap Store version is price ambiguous as well. I installed it and did a quick job which you can see here:
It seems straight forward and it looks good to my untrained eyes, the drawbacks that I did notice were lack of support for my Intuos 2 and the smallest brush setting was too big for detailed work like trees (it would be nice if you could select an area to apply or erase the effect). Also it has an unconventional save dialog, it all but forces you to save it as a new file rather than writing changes to the original file so that could be a good thing.
If it truly is free than it is a pretty good app, but I wouldn't buy it without the ability to be more detailed in where the effect is applied and graphics tablet support. I guess only time will tell if I get nagged, but I believe that would be against Crap Store policy so I don't expect to.