I would argue that the degree of courage Meryl brings to this role is exactly equivalent to the degree of resistance we have to aging as a whole, not only as expressed by popular culture but in the recesses of each of our own hearts.
Today, in a new time of budget wars, The Iron Lady's depiction of draconian cuts as feminist guts is chilling. What Thatcher called "harsh medicine" meant one thing for the poor and another for the very powerful then, and it still does.
Progressives will likely take umbrage with the movie's glorification of Thatcher. But in the end, Thatcher's obstinacy becomes her downfall. No matter how the movie glorifies her rise to power, her fate is the strongest indictment of her character.