it works well against some guys and not against others. James Shuler who fought Hearns had that defense and Hearns landed body punches which changed the position of the arms just enough for Tommy to land the right hand perfectly. Body punching works well against the cross armed defense, if the punches do damage.
and it kind of limits your defense. its either your head, or your body, if you're fast enough to bring your arms down. i would never be able to use it