Critics seem to love the fact that they did the unexpected...
Made the focus be firmly placed on all those individual characters, and the ultimate sacrifice the previous episode tipping the political tug of war to Toranaga's site with almost no blood being shed (the very opposite of the samurai/warlord mentality about honor coming from the battlefield).
The cinematography alone was amazing.
And leaving lots of little clues about our main character without even telling you whether he eventually ended up in England or stayed in Japan for the remainder of his life, very faithful to the spirit of the Clavel novel if not the actual execution.