This is kind of like the hippy version of a vodka Red Bull. It has alcohol and caffeine (at lower levels than a vrb) and it also has nutritional aspects from the kombucha.
Unity Vibration makes two flavors of kombucha beer: ginger and raspberry. I tried their ginger beer. It tastes like a natural ginger ale with a slight twinge of funk/sourness, but hardly noticeable. It had more sweetness than I was expecting, but not as much as a soda. I was expecting it to be a sour beer. Their beer doesn't taste like any kombucha I've ever had. The ginger wasn't as spicy as a Bundaburg or Stewarts ginger beer (non-alcoholic, used for ginger flavor comparison only), but definitely more flavorful than a mainstream ginger ale. It was more like a candied ginger than a spicy ginger. If I hadn't read the label, I would have had no idea it was 8.0% alc./vol. The beer tastes and has a mouth-feel more like a lambic or a cider than a typical beer. This is probably because of the addition of ginger, residual sugar, and the open top fermentation in oak barrels. 
