The show, which was a real shake up for the franchise following Stargate SG-1 and Stargate: Atlantis, never quite caught on with viewers, possibly because of its darker tone and more serialized nature. It is unfortunate, as in many ways it was the strongest chapter in the franchise's long history.
This, of course, follows the recent announcement that the network had canceled Battlestar Galactica spin-off, Caprica, as well.