First, The Passage is a tragic character-development episode which focuses on the sacrifices any military must make, and, thematically, is very well placed in the political metaphors of the third season story-arc.
Second, I will respond to Glaskas from Sweden. Galactica and the colonial fleet have limited manufacturing technology, energy, and foodstuffs available to them. They do not have Miles O'Brien, Leonard McCoy, Spock,or even a home-world, let alone a federation to draw resources from. With all of the radiation in outer space, why should it come as a surprise that they might face a food shortage and an enormous radiation cloud against which they have limited defenses. I see not discontinuity here.
Third, it goes without saying that this episode offers one of Luciana Carro's series-best performance. Sackhoff also contributes very nicely to this one.
Fourth, If you tend to be easily affected by depressing stories, you may want to avoid BSG's third season. Episode after episode... ai ai ai.