Well, sorta. He knows what it's like to be in a war zone for 4 months, getting 3 purple hearts for three little scratches that didn't even get him a day off.
Kerry did some 'good' stuff while in Nam. But that is overshadowed by his grand efforts to get those 3 purple hearts so he could get out. And it's overshadowed by the lies he told about the guys in Nam once he came home.