It doesn't make wine fizzy, it's a breath speeder. As you know, wines are supposed to breathe before serving, but people are in such a hurry getting drunk of good wine that they can't wait the time needed for decanting.
I got a Soda Stream as a birthday gift almost two years ago. Haven't opened it yet... I suppose it might be a good alternative for commercial soda's to make fizzy beverages out of home made juices, free from additives. As someone said, supermarket fizzies may be even cheaper than the aroma substances.