I felt this season took a little bit of getting into. Better than the 2nd season, at least for me, and then ending kept me on the edge of my seat. It's hard for me to keep all the characters in my had as there are so many of them with such unique dynamics, some of the time they take a side role and at other times brought to the forefront. I think 12 episodes is correct length for the arcs any longer and I think it would drag on too much.
Special abilities, dystopian present, and the constant thread of mystery.