The first half of the first season of SGU was absolutely awful. Since then SGU has actually been pretty exciting and entertaining, with actual 'sci-fi' stuff happening, but unfortunately it had already lost 75% of it viewers within that first half of season 1 and its fate was pretty much sealed.
Add to that, Syfy playing a game of musical chairs with its schedule and giving it minimal promotion (instead focusing on monsters and wrestling instead), couldn't have helped either. Many people I know who watched the show didn't even know the show was on at times, and it's frustrating trying to pickup a continuing story arc halfway through, so not surprisingly many didn't bother.
I thought SGU was a great innovation for the franchise to make, they couldn't keep doing the exact same format forever. Unfortunately SyFy (with bigboy NBC input) utterly screwed up. Not that they care, they're going after the lowest common denominator now with shows like wrestling, reality ghost shows, and similar rubbish.