This show is legit science fiction television.
If you don't know the show, here is the premise - alien invasion, civilization as we know it is destroyed. The humans still left fight for their survival and to form some kind of resistance against insurmountable odds. It is about family, loyalty, courage and pompous speeches about American history sincerely delivered by Noah Wylie. Mostly it is about kick-ass scary aliens. Some of the freakiest I've seen in a long time.
Being a summer show, they don't have as many episodes to develop their very complicated story lines, so sometimes the pacing is a bit off or rushed, and can get confusing - but don't let that stop you from watching.
Season 4 has been a bit uneven compared to the previous three, with our hero group of the 2nd Mass divided and conquered almost immediately as the season begins. The handling of the multiple stories and the unusual developments with the main character's daughter Lexi, left the season a bit saggy in the middle - but stick it out to the end. Sunday's two-part season finale was fantastic.
With one ten-episode season left to go, next summer will surely bring an end to this epic struggle - one way or another. The show has been reluctant to kill the core family members - but definitely not other beloved main characters - so knowing this is the end, I'd say all bets are off. No one is safe and everything is at stake. It really is the best way for a good show to go out and become great.