This episode starts to take the series in a new direction-working with the rebel faction of the cylons. I chose "pivotal" to describe the episode for the following reasons:
Despite being enemies, Natalie will trust Adama's word(sign of things to come?)
Roslin bridges the gap between herself and Kara,actually asking for help.
While each side plots to betray the other, a cylon(Natalie) is the one that wants to break that cycle.
The final four we know are getting nervous. What happens when they get exposed?
Roslin brings Baltar back in the mix by having him go with her to the baseship.
I loved that they ended the episode with the baseship jumping away, with the President and half Galactica's pilots aboard. This show continues to create great story arcs that last several episodes rather than stand alones. It gives the time needed to tell the stories well and in detail.