Since no one has said so yet, it seems necessary to add this.
The series is an excellent drama, in every way - no doubt about that. Well worth watching.
BUT.
And that is the point: The subject of this drama is politics, international affairs, government, intelligence - and these are largely absent from the drama.
So if you are prepared to enjoy a view of the events from the perspective of the personal lives of the main characters, then all is fine. But if you were looking for more than tenuous references to the events and forces at play in the world, and an account of how the characters of the story were involved in those events and forces, you will miss something...
This is not to say that it's a bad drama - it's still excellent. And lavishly designed and produced.
But those political events and forces were of historic importance. At a time where the world was still strongly driven by ideological currents, and there was a ruthless struggle for world domination.
In my view, that is even higher drama, and I missed those connections.