It's a notorious "bogeyman" in the US where dental standards are concerned.
Apparently in areas where it is most popular (can't remember - the Carolinas, Virginias or somewhere like that) the teeth are falling out of kids and teenagers heads at a very non US-like rate. Sound like a moral panic type thing to me though.
Haven't had it myself and haven't ever seen it for sale but I believe it is ridiculously sweet for a start. Basically, like a very sweet 7 UP I think.