To say that Nano is without its problems would be absurd. Only time will tell whether the developers will find a good solution to Nano's flaws. If they don't, there may eventually be a major theft that will cause people to lose faith in it.
Nano's zero-cost, high-speed transactions are its best aspect. I myself am not willing to dive in and invest a large portion of money in this cryptocurrency, however, I'm keeping my eye on it and feel that it has a good chance of success.