This post by Andrea at A Garden of Nna Mmoy delves into the different types of Sci-Fi and where battlestar Galactica fits in. Excellent reading!

To Infinity and Beyond: A Sci-Fi Neophyte's Guide to Battlestar Galactica

A brief excerpt:

You know who you are: you watched Star Wars and never really got it. You've seen Star Trek but frankly found it kind of silly. You've never wandered, even by accident, into the science fiction section of the bookstore. You live, fully grounded, in the world of realism. Both your actual and imaginative lives have sensible plots, realistic characters, mundane technologies, and stable narrative arcs; and the only monsters you're afraid of are the ones hiding behind bushes late at night.
Yet here you are, watching Battlestar Galactica, and somehow enjoying it. How can it be? More importantly, what the hell is going on?

Really: go read the whole essay.