Well, with oxalis it's always going to be sort of a trade off. Any benefit you get from the vitamin C content is offset by the risk of kidney damage from the Oxalic acid if you eat too much (same as actual sorrel). It'll work if you need Vitamin C, but there seem to be safter alternatives.
It's sort of related to why I think, if they could REALLY work out a way to make it shelf/refrigerator stable*, get the general public used to the different taste, and up production a LOT, Lichi juice would probably be better for most people than orange juice. It also has Vitamin C (in fact, it has four times as much as oranges) but DOESN'T have citric acid, so it's easier on the stomach, which is a big concern for people like me who get acid indigestion VERY easily (while I CAN use lemons and limes culinarily or in beverages, because they are diluted so much, most oranges are too acid for me to eat as is without severe pain. I'm pretty much limited to some of the sweeter types of mandarin and clementine, like the Dekapon (Sumo) whatever that other Japanese one that is like a Dekapon with seeds is called (begins with an "m", NOT minkan) REAL ushu minkans (i.e. the extremely tiny, nearly red kind they grow for canned mandaring orange slices. and so on (theoretically completely acid free ones like the sweet lemon, sweet lime and mango orange are edible by me, but with no sourness at all, I don't really like the taste.)
*They DO make bottled/boxed lichi juice, but it's usually either mostly apple juice with a bit of lichi for flavor, or loaded up with preservatives. On it's own, lichi juice ferments too fast to be really feasible as a grocery product, and it doesn't respond well to heat.