You've got to watch BSG from the beginning on DVD. It is about as un-Star-Trek'ish as it gets, and still be set in space.
There has been exactly ZERO aliens so far. It's been nothing but the Cylons chasing the humans, lots of empty space, and a few lousy planets. Almost every episode has bearing on the story arc. There have been almost no "stand alone" episodes yet, save for a few about internal fleet politics between the military, and the surviving government, and one about the black market that's sprung up in the fleet with some very dark undertones about prostitution and slavery.
The head "Good Guy" Commander Adama (James Earl Olmos) actualy staged a military coup against the "Civilian Government" at one point, when things were getting out of hand.
It's insanely edgy, and very dark, without being "too dark". (As a few thousand survivors fleeing the genocide of BILLIONS of humans ought to be...) The new BSG is one of the best things on TV period, not just Sci-Fi...
It's much more "people sci-fi" than it is "space" sci fi. Serious crap going down in the fleet as people struggle for power, to survive, etc. is just as important a plot as the Cylons who persue them. And it's not the original 1970s BSG "Oooh, there's criminals on the "disco ship", so let's send Face.. I mean ,Starbuck to investigate!" kind of crap either.
There is a Baltar, the guy who betrays humanity, while he's a weasel, he was initialy duped into it, so he's not purely evil either, so he's got major shades of grey to his character. (Plus major mental illness, and funky stuff going on.)
Other interesting tidbits:
The Galactica is insanely happy when they run into another surviving Battlestar, the Pegasus. However, things go downhill fast. The Pegasus is not run like the Galactica...
There are "Human Cylons", and I was VERY LEERY of this, thinking it was a cop-out to save on the FX budget, but instead, it's made the whole show. The paranoia that there's "sleeper agents" on the fleet is awsome.
The Colonials/humans are pagan pantheists with multiple "gods", even though they wear suits and ties and pretty regular clothes on the show, it's wierd watching one of them "pray to Athena" or "Zeus" etc. However, the Cylons believe in the "one true God" and his plan for everyone. Very freaky deaky...
If you remember how cheesey and lame the original 70's BSG was, this one is just as dark, edgy and cool as the original was awful...
The reason the show dosen't grab people halfway in is because it's not very effects driven, so while one particular show may be earth shattering in terms of a plot twist, there may not be lots of visual "WOW" factor to hook someone watching it for the first time.
Don't get me wrong, there is plenty of visual "WOW", but it's not just for the hell of it every show. We only get the light show when a big battle or lots of space travel furthers the plot.