It's fermented alright. Better than any other ferment I've made, so I'm guessing it has all the benefits. It may have a different name, but the mushroom or scoby will work in fruit juice, in the refrigerator, to make a wonderfully fizzy, tangy drink. Fermented juice is probably more nutritious than fermented tea.
These scobies only made a few batches of kombucha the traditional way that tasted any good or were fizzy, so I don't now how long it will last, but they're big, plump, rubbery and prolific.
I'll keep trying different juices and post the results. Are you trying some?