This entry contains a couple of generalized and thematic quasi-spoilers for Battlestar Galactica, especially for the first half of season 2. Also, at the end of the entry, some even more generalized quasi-spoilers for the first 150 pages of Tigana.
(I've given up on the idea of doing one monolithic writeup of all my BSG thoughts; I'm hoping that by tackling smaller individual pieces I'll at least get some of it done.)
One of the things that's been really impressing me about BSG is the way it handles redshirts.
Specifically, when someone dies on this show, their death generally has an effect on the people around them. Even if the character who dies isn't someone the audience has come to know well, they're someone that the other characters know well. And the show helps the audience to care about those deaths by showing us the effects of the death on the characters who we do know and care about. It seems to me that in most sf TV--and for that matter, most drama--the major characters generally pretty much shrug off the deaths of minor characters. Par for the course. On BSG, even though most of the protagonists are combat soldiers who've just seen billions of people die, the individual deaths of their friends and compatriots still hurt them.
(Which I think is a very useful lesson for fiction writers of all kinds. I've always thought that to get a reader to care about what happens to a given character, I had to let the reader really get to know the character in question. It hadn't quite occurred to me, at least not in so many words, that really all I need to do is get the reader to care about how that character's fate affects other characters. Which is still hard, but maybe a little easier than spending a lot of pages getting to know a minor character, and doesn't distract as much from the focus on the main characters.)
I kind of think that this is part of a more general thematic idea in BSG: the idea that actions and events have consequences. Things that I would expect, in a normal TV series, to be minor sidelights keep turning out to have major effects on the direction of the plot and the lives of the characters. That kind of thing can be taken too far for me (my standard example being the time in Hill Street Blues when a major character was shot and killed completely out of the blue); in fiction, I don't want the plot to feel completely arbitrary. But when seemingly inconsequential character decisions lead gradually and plausibly to very real consequences, and when things that seem to be dangling plot threads turn into major plot elements a couple episodes later, I like it a lot.
I think all this also ties in, though somewhat indirectly, with complexity of character motivation. I seem to recall that people associated with the BSG miniseries made a bunch of comments about how great it was that the protagonists were flawed, and I certainly approve of flawed protagonists; but I approve even more of the villains being multifaceted, interesting, and hard to wholeheartedly hate. I know I'm a sucker for that kind of thing, but I find it particularly impressive that the show can get me to root for a Cylon even after the Cylons killed billions of people.
On a side note, I'm finally reading Tigana (after 15 years of recommendations from all and sundry), and liking it a lot--and seeing some of the same kinds of things there. I can't quite articulate this yet, but the ways in which the main characters care about, and feel responsible toward, the minor characters, and the ways in which seemingly irrelevant events later turn out to be central to the story, feel to me somehow similar to some of the things BSG is doing.