I saw this series belatedly; it's fairly good, not exceptional, sci-fi fare. Some of it's philosophic moments are more profound than usual and the intellectual level of the discussion shows that the writers actually used classical allusion; or looked up the references anyway. Apart from that the characters are engaging and the plot's the usual ever-present danger but no-one important ever gets killed stuff. The problem is that the series is unfinished, apparently pulled before being resolved; this is a problem because the essential issue was that if they couldn't find a cure within five years then the population of the Earth would die of an alien plague. The discursive way the story writers approached the central theme indicates they expected to ride this horse for about 5 years themselves. But it stopped after one partial season, 13 episodes. Which means that the Earth actually died somewhere around 2004, and no-one noticed! I always knew media barons were bad guys; but killing off the Earth on a marketing decision is too much! This habit has become almost typical of American television's approach to SF ever since, everything good gets a short run and pulled, The Chronicle and Firefly stand out as other examples. They could have made one more episode of Crusade to solve the plague and wrap it all up at least... Boo, hiss!