I've used it quite a bit, idoser to be exact. They do work to some extent, you need to listen to the frequencies for anywhere from 20min-1hour and it's a hit and miss with some of them. They do work though and it is quite surprise when you take your headphones off, stand up and walk around the room in an altered state.

For the amount of time needed for the effects to kick in and the hit and miss factor, I'd rather just spend the $10 on 2 hits of lsd and go tripping in the forest for 8 hours 8D.