Cryo treatment is a computer controlled process of taking treated parts down to -300 degrees or more (-320 is about max). Its not a surface coating as with other process, rather the whole part, through and through, is treated and greatly reduces wear. You sacrifice nothing in braking ability but you severely reduce warpage and wear which gives your brake pads and rotors a much much longer life. It also aids in heat dissipation which would be a benefit for brakes as well.
Do a google search and you will come up with a lot of good info.