You would suffer a large number if acquired the incorrect size. If you bought a size too big, can injure your feet. If you bought a size too small, it is bound to hurt a person as all right.
If you carefully view the Five Finger shoes, you may notice that comfy have five seperated toe holes for every toe of individuals. Yes, this appears really odd, difficult to imagine that how the designer might well have thought of such a way. But indeed these seperated "fingers" can build your toes move independently. For example you have much more flexibility in your feet, especially your toes.