Day-Lewis' Emancipator is kind and wise, but also conniving and practical, and represents some of the better aspects of the America's political system, namely that it tends toward a more just society over time while (usually) refusing to engage in factional fanaticism. In several conversations with other political figures, he steers away from ideological purity and toward a path of practical wisdom.
This focus on Lincoln on a horse-trading politician rather then a martyred saint is especially interesting in for a film released in 2012. Despite widespread cynicism about the ability of national political leaders to get anything desirable accomplished, the movie's story rests in large part in demonstrating how the sausage factory of Washington can be redeemed with lofty goals and hard work. Of course, the movie does depict most of the politicians in 1865 as either spineless, venal, or stupid, but that's how you know it's based on actual history.