Research says that it's a bunch of dog squeeze ("theatrical placebo").
I have heard people swear by it, but have not had the pleasure myself.
However, I am as big a skeptic as they come but I have personally used a number of Occupational Therapy techniques with my special needs child that I thought sounded wacky-but were very, very helpful.
There are certainly things that have not been proven to exist, and observable phenomena that don't have an official name-but that does not mean they don't exist.
For example, there are children (mostly special needs, but not all) who have very real problems dealing with certain textures of food, the feel of certain fabrics, certain noises, etc...It's called Sensory Integration Disorder-but it can't be "proven" to exist. But anyone who has seen this in their child knows it does exist. You can observe it, though or elements of it anyway.
I won't go into the details here, but there were several therapeutic OT protocols that we used-meaning me-first hand, with my child, and I thought at first that it was completely insane. Had I not seen the improvement with my own eyes, on my own child, I would have never believed it would make any difference.
So there's that.