I may have tried it once, years ago. I don't drink it at the moment. Don't remember if I liked or hated it, since I don't know what brand or flavor I had.
It's recently started to appear in the UK, mainly in health food shops which is slightly ironic. While it may have some beneficial properties it also contains polycyclic aromatic hydrocarbons which is a carcinogenic also found in tobacco and grilled meat. It also contains a lot of caffeine.
Like everything else, it's probably best consumed in moderation.