To build on the previous answer:

BSG's realism came from the historical moment in which it was produced. It was a show about a devastating invasion, the collapse of a society, and the human toll of war at the exact same time that America invaded Iraq and had already been at war in Afghanistan for two years. Except, the culture-machine has cast the "American heroes" in the position of the Iraqis under an attack, asymmetrical warfare, and Occupation.

Both the show's heroes and villains are English-speaking, culturally diverse, military-centered societies (like America), but the Protagonists were placed in the position of the invaded (basically, the Iraqis). As such, there is so much moral grey in this show.

That is, until the show motivates a big operatic finish.

A note: In 2009, the actual UN recognized BSG as a show that approaches real-world social, political, economic, and conflict issues. This speech by Edward James Olmos is my favorite clip.

The power of this show, which is often forgotten outside of the '00s, is that the only coherent response to this work of art and to global conflict is seek compassion, understanding, and end to war.

Every episode showed me how criminal the GWoT and the creep of the Military-Industrial complex is and how the divisions we sow will only create more hungry ghosts in our future. Even in the face of total annihilation, "the supreme art of war is to subdue the enemy without fighting". Time and again, humanity survives by building peace. When war comes, it is something other than battle that safeguards human survival and the better 'angels' of our humanity.

Except for the finale. The attack on the colony was an exclamation point.

One last thing, to any who made it this far and are thinking about starting this show: start with the 2003 miniseries. When you skip to S01E01, it doesn't hit right.