I have used it. nontoxic for one, non solvent for another-its water based.
works great on straight cast iron.
you do have to treat surface once the rust is gone or it will return, uses chelation(similiar to electroplate without the electricity)

careful soaking painted stuff in it for a long time-I ruined a 5 gallon can as it turned the paint into goo (soaking it for days though)

can get expensive for bigger parts if you need to soak something and the need for gallons of this stuff