I've got a bunch of a similar product (Aluminum brazing rod, essentially); it works, but is not as simple as the adverts say.
Tips if you go for it:
A stainless wire wheel mounted in an electric drill makes cleaning the surface easier. The surface has to be completely free of corrosion, anodizing, etc for the stuff to work.
Heat the snot out of whatever you're joining. Near as I can tell, the more heat the better (up until you vaporize the aluminum you're working on, anyway.)
Have something underneath to catch drips. The drips will be molten metal, so be damn careful, and watch for splatter.
Have a small angle grinder with an abrasive flap wheel handy for cleaning up the joints. They never seem to come out looking worth a damn.
Once you do get the things joined, the product seems to be fairly robust (though to be fair, I would not use this on anything critical. I'd get critical stuff welded properly.)
p.s. Forgot to mention that some of these companies have similar products for other metals as well: steel (don't know about stainless), bronze, etc.