The season went from being Samurai Jack for adults to being your usual action oriented adventure story.
Not bad, just not what I hoped for. It's still perfectly serviceable, enjoyable in many occasions. Hell, every episode has something valuable in it, that I will not deny.
The main problem this season had, even a bigger issue than the time, was its loss of identity. I am 100% certain that had this continued to follow the Samurai Jack formula with a more mature tone and a sense of continuity 10 episodes would have been perfect.
Samurai Jack was always style over substance, and it did that greatly. Trying to add so much substance was a bad move.
And this is coming from someone who loved season 5, despite the underwhelming ending.