The reason that I didn't like it is because it was extremely predictable.
In the first scene, when the main character shows up and takes the truck, I knew the Nazis would arrest everyone but he would escape, and that's exactly what happened.
The Nazis were portrayed as bad, but they were not nearly as bad as the Nazis were in real life. The Nazis ground occupied Europe down in the dirt, looting all wealth, and forcing millions into slave labor camps that killed them off by slow malnutrition. In the TV show, occupied Nazi America was a pleasant place, just as wealthy and prosperous as the United States in our reality. While they mentioned that crippled people and terminally ill people are euthanized at institutions, this was the only hint that anything was different. And none of the characters seemed to really care about this, until one character finds out that his son has a nervous disorder, then he suddenly cares. Which makes him an unrealistic Nazi, because a real Nazi would be the first to ship his handicapped kid off to the death hospital.
The Japanese were also not portrayed as all that bad. They killed a Jewish family, but only because they were trying to gain information from a Jewish man. It was made clear that typically the Japanese did not persecute the Jews, or blacks, or any other non-white. This is not accurate, the Japanese were just as racist as the Nazis, and they murdered millions of Chinese because they thought of them as racial inferiors. They also raped millions of women, and they brutally abused and starved prisoners of war. None of this kind of brutality was portrayed. There was one scene where a Japanese soldier forced whites to wait behind Japanese people for taxis at an airport, that was the only hint that the Japanese were oppressive, and that's pretty mild compared to what they really did.
While there was a resistance in the show, they never explained what exactly motivated the resistance fighters. They never talked about the bad things the Japanese or Nazis did to them to cause them to join the resistance. One guy was arrested, his family was murdered, but then he doesn't join the resistance he just makes a fake piece of Indian jewelry to make money from a naive Japanese couple who collects American cultural artifacts.
Also, the entire main plot about movies that showed an alternative universe where the Allies won the war was a reminder that this is an alternative universe story, and it really broke the fourth wall as far as I'm concerned, reminding us that what we are looking at isn't real, but that our world is the real one. This was reinforced at the end when a Japanese character simply teleported into our real world, where the Allies won World War II, and to make the stereotype all the more obvious, there was a newspaper headline about the Cuban Missle Crisis. Of course, because it's 1962 and that's the only thing that happened in 1962 according to Hollywood.
