Rosewill usually chooses inferior OEMs for most of their PSUs, which is why their build quality and reputation is so poor. Not all of their PSUs are bad though, it just depends on the OEM used for a particular model. Their higher-end ATNG based models are quite decent, and the RP500-2 is a particularly nice one, but with better alternatives available, one wouldn't really go for any of them.
Overall Rosewill's PSUs are mediocre at best, and definitely not at home in a gaming system. However, they are a brand to consider over others like Deer, Allied, Powmax and Dynapower. The latter even have units with bogus UL numbers!