I've watched both seasons of The Colony and I enjoyed it greatly. It's fascinating to see what people do when they are put under huge amounts of stress and pressure, and the modern day idea of a viral outbreak is a perfect setting for such an experiment. The Colony brings out the best and worst in its participants, and makes for great TV in the process.
Personally, I enjoyed season 2 more than season 1, but if you're new to the series, I would start from the beginning. I've heard that season 3 is coming, and I couldn't be happier. Well done Discovery Channel!