It's not an exact replacement, but it's as good as it get currently... The main function of the foreskin is the act as a gasket and as lubricant during copulation. By stretching the skin out, you restore these two functions. You also undo the keratinization caused by the exposure of the glans. So by restoring, you are undoing a lot of damage.
Of course an all natural foreskin is better than this (mostly because it contains specialized nerve endings) but restoring is the best option for men who want to reclaim their sexual pleasure... it's not perfect, but it's a substitute until foregen is finished with their product.