Just like with many PSU manufacturers, Rosewill does have PSUs that range from absolutely shitty all the way to some of the highest quality PSUs you can buy. Generally when I do see Rosewill PSUs get recommended, it's usually their Capstone series.
I wouldn't get one. They make some really bad PSUs and some reasonable ones, but the reasonable ones are usually around the same price as a good Corsair or OCZ unit. You can't just say, how are rosewills PSUs? Without saying which ones. You can get a Corsair CX series for the price of a okay rosewill.