I went into this show thinking it was going to be like The Man in the High Castle, another Great alternate history show. I was wrong. What I got instead was a very thought-provoking and fulfilling show. The initial few episodes, may come off as boring to many people, including myself. However, these initial episodes set the stage well for the latter episodes, and the show delivers a satisfying conclusion. The show uses the Alternate-History plot point in moderate amounts, never using it as a gimmick. It gives us information in sparce amounts, and allows you to ponder over what what may be happening elsewhere. Also, the story isn't a metaphor for the current political climate in the US, which some people have suggested it to be.
Tl;dr A Great and well-crafted Drama with a good payoff