And both of those drinks should work just fine, though not all drinks do. Their site lists milk and Frappuccinos as liquids that won't make usable bubbles. That's fine. Milk bubbles sound disgusting.
How well does it work? "Since the volume of the bubbles is tiny, to appreciate the taste of each bubble, one needs to use a beverage with very strong flavor," CEO Dat Tran told Thrillist. "Moreover one needs to have sensitive taste buds. Kids are more keen to the flavors."