The Man in the High Castle is an alternate reality TV series where the Axis powers won World War II, thanks to the assassination of Franklin Roosevelt and Heisenberg developing an atomic bomb before the Americans. Fast forward to 1962, and America is mostly under Nazi control and the west coast is controlled by the Empire of Japan.
The series started with great promise, but it spent 4 seasons mostly being a soap opera while the main story advanced very slowly. As I watched the final episode, my first impression was the story had not advanced much beyond the end of season 3. However, the show figured out a way to conclude the series properly in the last 10 minutes. The final scene is a little confusing and I'm not sure exactly what it is supposed to mean, but I suspect that it is a cliffhanger for a possible TV movie.
I did find it entertaining. This is a very much character-driven story, and there are several characters whose arcs are significant. However, I was expecting something a little more exciting in a science fiction sort of way, and the show never gets there. Instead, by mostly focussing on characters and drama, the show doesn't achieve the full potential of its premise.