So, BSG has been, without doubt, my favourite series, probably ever. Well, perhaps tied with Firefly, but firefly never had the chance to grow and develop the complexity that BSG had. Firefly it was all in the back story, BSG was able to take the back story and develop it while you watched. And bring you more bits of back story as it went along.( No spoilers as such, but does include a plural that might bug some people )
I can't really do it any more justice than to link to Howlsthunder's post (spoilers) which says all I want to say.

I look forward to The Plan and Caprica. And it's one of the few things I'd want in HD to watch on a really big screen, because it is beautifully shot.