I liked it. The show brought up a lot of points. Intelligence agencies wield an enormous amount of power without meaningful oversight or direct election by the populace. A right wing conspiracy could very well take out our government by coup, we are not immune. Intelligence agencies routinely manipulate and misinform politicians, and represent a different polity than that elected.
Dar was portrayed as having involvement only in the disinformation, not the blood shed or the bloody coup. Also, with the twist on the twist, Dar was possibly right because Keane is not what she seems. After all, we vote for a generated mythology, and the actual person and underlying motive is always a mystery. I suppose you could toss the Trump/Russian connection into the mix, albeit with the liberal female Pres rather than a conservative Pres. They said the recent election results were not in when the show was wrapped. I think they presumed Hillary would win. They also said they modified the ending due to the actual election results, but did not specify how. I do rather wonder why the obnoxious talk show host was not immediately arrested.
Keane was portrayed as an independent counsel, a constitutional lawyer, and independently wealthy in previous seasons. The fact that she could be some kind of mole, herself, with an agenda, rather than the pure political naif, was broached at the end when things deteriorated into a witch hunt and suspension of rights. Kerry staring at the Capitol and wondering was a chilly finale.
I thought it was good and a good setup for the next season, but I will miss Quinn. I imagine Dar and Saul will be sprung at some point.