The world would have been poisoned. The only possible positive you could wrench from this exchange would be a total lack of overpopulation now.
You don't "win" a nuclear war. So what if one side outnumbered the other and lets say for some reason only one side gets obliterated and the other is completely unscathed. Do you really believe there would be no consequences for humans if 1/7th of the planet is a radioactive wasteland?