There should be a number of posts on them if you can find them. A few people like them. A lot of people hate them, most of whom haven't tried them. Unless you're trying to solve some specific problem (live in Tack City or something), I wouldn't bother.

These have always come accross as a too-good-to-be-true item, like all the Ronco stuff that looks great on the infomercial, but not when you try to use it.