I really liked season 1, I watched it almost back to back to back over 2 days when they were On Demand. I tried watching season 2 and just couldn't get into it as much. Season 1 was more realistic. Season 2 was a group of people dropped into a Viral Pandemic almost. Give the first season a shot.
I just found it on Netflix. I kinda like it. It shows how unprepared some people would be. I mean I know it is not nearly as bad as what it would be like if S really did HTF , but makes you think about somethings.