Technically, Rooibos is not a tea proper (see: Tisane), but it does contain anti-oxidants, and indeed contains more of these beneficial chemicals than green tea.
Advocates of Rooibos attribute many medicinal properties to the plant, and claim that it is beneficial to the treatment of diabetes, high blood pressure, irritability, headaches, stomach cramps, disturbed sleeping patterns, insomnia, nervous tension, mild depression or hypertension, liver diseases, allergies, cataracts, and skin irritations (just to name a few).
As for the taste, many (including myself) find that Rooibos has a light, somewhat fruity, cinnamony taste. It is most certainly a self-drinker (or a tea that can be had on its own, with nothing added in).
The infusion created from rooibos is a bright, rich red color, garnering it the nickname "Red Tea".