I've never found much info. Farberware started making them in the '60s, and there are loads of these things floating around thrift stores, garage sales, and eBay for very little money. Some have rotisserie motors, some don't, and there are several sizes. They're practically indestructable, so age isn't worth worrying about.
Certainly not as good as a real grill, but if you want/need to grill indoors, and only have an electric stove, I'd say this is a pretty good solution. I've used several sizes of them, and have always been at least satisfied with the results.
Beats the hell out of a George Forman grill, that's for sure.