Overall the series was great but the finale left me conflicted. It was very anti-climatic.
My biggest issue by far is how they "resolved" the entire plot by having Toranaga revealing his plan and how he will win. It was very unsatisfying and, frankly, feels unfinished. With that said, I did appreciate the reveal that Toranaga is not the honorable man he pretends to be but rather every bit the power hungry villain that the the regents claimed.
Then there is Blackthorn who is presented as the protagonist. And so the viewer expects him to do something, to matter. But nope, he's just a distraction. It may make sense and be "realistic", but it was very unsatisfying.
***HEAVY SPOILERS AHEAD***
The reason why Toranaga's endgame was shown in quick visions and not a huge battle, is because Toranaga won (or will win) without having to go to war.
I personally would have preferred a huge battle scene for the visuals, but the way it was done shows Toranaga's genius and conniving, that he will do whatever it takes to get what he wants.