When I love a story, I usually criticize the heck out of it. I love BSG (sometimes), but as it draws to a close, I don't want to criticize it; I want to praise it. Maybe that's because, while it fails in the usual ways, it succeeds uniquely.
BSG pulled off two things you almost never see in American TV sci fi.
1) Lots of significant death. This is only appropriate for a story about the near extinction of the human race. The series started with about 50,000 survivors and ended with less than 40,000. While it's hard to say what's "realistic" in this context, this attrition has the ring of truth. This is a population on its way to extinction (bar miracles), and the show consistently remembered that basic truth. Nor was this erosion just a number game. I've criticized BSG in that past for having too many characters to develop any of them fully enough, but the advantage of the vast ensemble is the ability to represent the human race. And the show, courageously, represented its passing as well as its survival. Let me just name off a handful of the significant, individualized characters it killed off (in no particular order): Billy, Dee, Gaeta, Zarek, Cain, Boomer, Cally, Tori, Roslin, Starbuck, Anders, Cat, Racetrack, and so many more. It killed off so many people there was no one to leave in command of the fleet when the principals went off to rescue Hera except Hoshi:-) Again, this was thematically appropriate and narratively braver than most TV shows dare to be.
2) Miracles. The reboot of BSG was always in an interesting ideological position. Its structure derives from a story that is inherently very religious, and--if I recall correctly--was created, in part, to be a tract on religious faith in a rather old, conservative American (Mormon?) vein. Yet the folks in charge of the reboot are, I think, rather secular, liberal adherents to science, reason, and moral relativity (in the sense of multiple, dialogic points of view). How to marry the conservative and liberal partners without ending up with schizo mush? Baltar's speech was (remarkably) wholly sufficient to the task. He debunks the secular scientists (one of whom he used to be) who would reject the obvious, undeniable evidence of mystical occurrences: the prophecies that come true, the resurrection of the dead, etc. There are more things in heaven and earth, he asserts, than are dreamt of in their philosophy. But so equally does he debunk the religious sectarian who seeks to appropriate these mysteries into the service of "God," "the gods," or any other reductive bid for "truth." There's more than they dream of as well. Finally, he tells us, it doesn't matter what you call it; it's not as if we're about to understand it, but if you refuse the reality of transcendence (of the inexplicable itself) when it's right in front of your face, you're refusing a vital part of life. Now, this may be pitched to appeal to me as an agnostic, but I admire the grace with which BSG managed to remain reverent to the religious context without descending into reductive religiosity. That's a balance I haven't seen another show pull off.
Good ending.