I watched this a few weeks ago, and I’ve gotta say, I’m surprised by the reactions here, especially this one. I though the show was very faithful to the book, or at least events the book talked about. As the book opens the couple in San Francisco have already broken up, and she’s already in Colorado. The Truck Driver is either already there on on his way, too. The show basically uses the history set up in the book to show what the state of the world is- they’re following that age-old maxim of visual media, show, don’t tell.
The most interesting actual change they made was changing the book-within-the-book into a film for the show, specifically, into newsreels that appear to be from our timeline. I see why they did that (again, it’s better to show the audience what they characters are seeing than have them just talk about a book), but in MitHC the “Grasshopper…” starts out seeming like the author has a window into our timeline, but as it progresses, you find out that the timeline of the “Grasshopper…” diverges significantly from ours. Sure, the Allies win WWII, but there’s a bunch of other changes to our ‘real’ history. I wonder if they’ll tackle that in the show. It would be a big thing to leave out, but given the route they’ve taken, but I wonder if they think creating fake-real footage would be too subtle for the audience. I’d love to see where they take it, though. If they do turn this into a full series, I’m on board.