Utterly blown away. I went in knowing a little about the original short story by Philip K. Dick, but I haven't read it. From what I understand, the show has significantly broadened the scope and ideas of that story, which is understandable (it really is quite short). I don't know how I feel about the whole parallel-universe cliffhanger ending element, but they were already heavily hinting at some kind of time-travel or timeline manipulation with the tapes so I'm glad to see them making the leap.
Serious sci-fi elements to one side though, what a whirlwind of a first season. The characters are brilliant and nuanced, the plot balances pace and tension expertly, and the setting is excellent. I love the idea of alt-history in general, but they've really run with it here. The whole Neutral Zone, in particular, is a great concept, both from a narrative sense and a world-building one. Similarly, it's great that we get to see into the lives of people on all sides. The stark differences between the day-to-day lives and the similarities in the behind-the-scenes politics between the Japanese and Nazi empires, as well as those in the Resistance versus the people just trying to get by in places like the Neutral zone, give the show a lot of nuance and an excellent degree of world-building.
From an acting perspective, the cast are brilliant, but personal standouts are definitely DJ Qualls as Ed who I really hope gets more screen time next season, both Cary-Hiroyuki Tagawa and Joel de la Fuente as the Japanese Trade Minister and Chief Inspector, and of course Rufus Sewell as John Smith. As a huge fan of A Knight's Tale it's just great to see him again, but he plays the role of an American Nazi so well. He's threatening and scary when he needs to be, but still human and weirdly relatable. His arc – from clear villain to man just desperately trying to keep his family safe – is a powerful one and a great take for a film about such impactful topics. You never end up rooting for the Nazis, but you do begin to understand how seemingly normal people could end up working for them.
I'm still not entirely sure how much I enjoy the romance plot between our "main" characters, Joe and Juliana, but I don't hate it either. Honestly, of all the plot threads hers is the least interesting in some ways, but she's a useful device for fleshing out the tapes and what they mean. The only other negative I have is that the show is so damn bleak. I get that it needs to be – and I really wouldn't change that in any way – but man does it make it a slog to watch. I don't think I've come across a less-bingeable TV show that's still exceptionally good. It's a weird combo but I'm looking forward to more.