This season really grabbed me after being underwhelmed by seasons 2 & 3. I felt a strong sense of direction and purpose. Cutting down focus on Piper was a wise move, as was limiting flashbacks to episodes where they are narratively useful.
I also feel like they weren't pulling their punches. This season had some real stakes, and both the physically and psychological violence hit hard. (Baby mouse... brrrrrrr.
The penultimate episode knocked me on my butt. The last episode kicked me when I was down. But the last five seconds made me yell "STOP. STOP IT." And then I cried for several minutes and I honestly can't remember the last time a show brought me to tears.