Ripple is prone to fragmentation.
You end up with piles of little "islands" of people that trust and can pay one another. Paying to people on other "islands" is troublesome and sometimes impossible.
There is nothing wrong with this. I have always though and history also indicates the same that having local currency complementing a more global currency is positive because it helps isolate your local economy from economic problems in other place. For example, the north of Brasil has a local currency and they have weather this crisis very well. Switzerland has a long tradition of private currencies and have achieve better prosperity (not the only reason obviously). Nowadays swiss companies have a private currency system that they use to lend and borrow between associates of the system, and all the industries acknowledge that it has been a key factor to mantain economic stability.
Having a local currency is very positive. It helps you isolate you from external shocks.