Once you get the gun I suggest taking a look at this link, it provides good info for making an initial assessment on the condition of your gun (which I assume is a revolver)
I own a recent model Rossi 971, since Taurus bought Rossi, and have put about 1,000 rounds thru it without a hickup. A local gun shop owner uses an older Rossi as his instore side arm and considers it 100% reliable.
Go to other forums tho and opinions on Rossi are more mixed. Some folks are just S&W snobs but not all. It seems that in the past Rossi has gone thru periods of good and less good quality control. Problems tend to be of the fit and finish variety rather than materials and design (which were often S&W knockoffs). Keep this in mind if you're getting an older gun. Recent model Rossis seem to be generally quite good. People who like their Rossi like the triggers, they point well, and are accurate out of the box.
Since the gun is free, spend a few bucks to get it checked out, and cleaned, especially if the history is uncertain. If you're wondering about the worth, Rossi have always been more of a value line so don't expect much. Just shoot it and enjoy it.