Magic shave does not reduce or slow down hair growth. It dissolves hair in the same way as Nair, but with formulations for scalp and face. I have given it a try, and it works, but it is not as smooth as a blade shave. I still have a sandpaper feel after using it, but to the eye it is smooth.
If you try it, read the instrucions and be sure to test a small area first to see how your skin reacts. Some guys cannot tollerate these products and end up with burns. I have never had any issues with it.