I am one of those that read the book back in the early '80s after watching the miniseries when it originally aired in 1980, read the book a second time years later, bought the miniseries on DVD and has seen it several times. Above all things, Shogun is engrossing. It has development and suspense as we learn about this 'alien' culture through Blackthorne's eyes. Characters are revealed, moving from 'alien' to sympathetic, from threatening to familiar. Sadly, this re-working has none of that. None at all.
The meanings of scenes are substantially reduced or completely lost. Pacing is gone. Development is gone. We are skipping along the surface, hitting the highlights and doing so from everyone's perspective at once. We know as much or more about the Japanese as we do about Blackthorne, which leaves nowhere to go, nothing to discover. In short, the storytelling disappoints.
The Japanese casting is excellent but the actor who plays Blackthorne, despite a great voice, conveys none of the sharp intelligence that used to define his character and drew Toranaga's interest.
The only caveat I can offer is that this is based only on the first two episodes as the rest have yet to air. I cannot, however, see things changing given the nature of these issues. The engrossing element, which was once the whole point of a miniseries, is gone.