Rooibos tea is a tea brewed pretty much exclusively from the plant Aspalathus linearis, and it is becoming a more popular beverage to drink in part due to its taste (being semi-sweet and less bitter than green and black tea) and having a low to no caffeine content, as well as marketing suggesting its antioxidant properties are healthful.
When looking at the main claim, the bioactives in Rooibos appear to be relatively potent antioxidant but even when tested in vitro (outside of a living body) they are not as potent as the green tea catechins; the main bioactive, aspalanthin, also has a pretty poor absorption in living models which limits how it can increase plasma oxidation capacity. The antioxidant potential of Rooibos is present, but both lacklustre as well as unreliable.
There are some potential benefits to drinking this tea even when low absorption is considered. It is said that the tea can alleviate intestinal distress and it does appear to have some relaxing effects in the intestines, but there is no evidence in humans at this point in time (and for that claim, peppermint would be a more prudent option). It appears to inhibit glucose absorption from the intestines as well, which may be an anti-obesogenic and anti-diabetic property, but no human studies exist at this point in time.
Currently, Rooibos is interesting due to being a palatable tea option but there is not enough evidence to support much health benefits associated with it aside from the standard beneficial (and small of magnitude) changes to unhealthy persons that are seen with any antioxidant compound.