Originally, these "toys" were created for kids that were autistic or suffered from AD. it's supposed to help keep them occupied, at least I think.
I do own some, my son came home from school fussing he had to have one. Now each person in the family has one, their own color. we found cool ones that light up, so we're lame, we like to watch them light up and glow. otherwise, they are pretty worthless...