In the beginning, it's a seat gripper. There's constantly something happening but by season 3, you already know that if the show is quiet for over 50 seconds, another bomb is gonna drop and devastation follows shortly after. Nothing ever goes the right way, it's just terrible turn after terrible turn. There's no down period where someone isn't fighting for their life or able to make peace. There are no happy feelings in this series, just constant dread. By season 3 I just couldn't take the depression anymore and quit trying to power through.
If you're into constant drama that never stops, people constantly dying or being tortured, plans to save humanity that always fail, this show is for you. I found it to be "too much" and too predictable. If it's quiet, something bad is about to happen. If they're in the final stage of a plan, something bad will happen and they fail. Everyone is constantly failing and dying. Too depressing for my taste.
That being said, it's well put together and has a good story line. If they could have just slipped in a few episodes where for at least 10 minutes, something terribly bad doesn't happen, I might still be in board but this is just too much.