I don't know how I feel about Nano. I know that I really like the concept. It is super fast transaction wise and there are no transaction fees which is incredibly amazing for starters. But I don't like that there was a recent hack that turns me away. Maybe I might invest later on but who knows
If you're talking about the BitGrail fiasco, everything is pointing to either the exchange operator (Francesco Firano) being totally incompetent and writing terrible code or him actually being complicit in the theft. I've seen absolutely no evidence that it was caused by any shortcomings in NANO itself though.