well, I'm no expert on PSUs, but I can name a few notable factors of a good PSU:
+12V power, multiple +12V rails
Active PFC (Rosewill 600W lacks this)
High efficiency (>80-85%)
High continuous power output (some makers list PEAK power output)
In addition, the actual maker of the PSU is important to reliability and stability. OEMs vary widely by company, and I think your Rosewill is made by SOLYTECH...I don't know much about SOLYTECH, but I do know a few good ones are TOPPOWER, FSP, Seasonic, and Enhance. Rosewill's other OEM maker is ATNG, who also OEMs for Coolmax (not exactly a reputable brand of PSUs)
I did check the specs on your 600W PSU and it does look pretty good, so I can't really say if it's bad or good just based on company specs.