Privately issued currencies are not a new idea, similar systems have been in place since as far back as the early 20th century in Sweden and the U.S. One big question is how such currencies will be regulated, especially because governments often phase out private currencies to retain control over monetary policy. There's also skepticism, in today's economy, whether private currencies could get to that kind of traction that would make them successful.
Another potential concern is the associated risk of permitting self-created currencies, as suggested by this project. With little to no regulation, it is possible this could cause volatility in the financial system, much like prior instances when private money ideas were considered and floated. Not all is lost for private currencies. In fact, they have a bright future as evidenced by the growing use of digital currencies such as Bitcoin, among others, and the concept of community-based monetary systems.