Joshua Rothman, writing for The New Yorker:
SodaStream could pose a significant threat to Coke and Pepsi. Selling soda is a weird business. It's dependent, to an unusual extent, upon mythology and emotion. Right now, people are fanatically loyal to their soda brands; they have emotional connections with soda that far exceed the inherent qualities of the soda itself. ("I had my first kiss while I had a bottle of Coke in my hand," Charlotte Beers, a C.E.O. of Ogilvy and Mather, once said. "Coca-Cola isn't about taste; it's about my life.") That's why competition in the soda business has centered so often on advertising and distribution, and so rarely on cost competition or on innovation in the product itself. Coke and Pepsi can't compete on price, because that might reveal what a hum-drum commodity soda really is (think of down-market soda brands, like Diet-Rite); they can't introduce too many new sodas, because that might suggest, unthinkably, that our soda preferences could be more ecumenical than they usually are. Their main priority is the preservation of the aura, which, however improbably, hovers around Coke and Pepsi.
Admittedly, I drink more soda than I probably should, but I'm not such a junkie that I feel compelled to make my own. (In fact, I like Coke and Pepsi equally.) That said, the SodaStream has long intrigued me. Seems like it's to soda nerds what the AeroPress is to coffee nerds.