Yikes!
The pace has picked up and the puzzles are expanded in multiple dimensions, rather than closing in. Miriam, Elias and Violet continue their search for answers with newly discovered adversaries.
The writing is solid and built for speed. Its focus is moving the plot forward, with less atmosphere than the earlier seasons, likely because it has already been established.
The serial nature makes it hard to gauge where we are in the story. I guess that reflects real life; you don't know how close you are to the end of an adventure or challenge.