I was very absorbed by this movie, although I think it is best suited to those with some interest in Japanese military history. One should always be suspicious of the historical accuracy of movies (hence the recent controversy over the Churchill movies and Viceroy House) and it needs to be seen in the light of attempts by the Japanese to come to terms with their participation in the SWW. However, from what little I know of Admiral Yamamoto it seems to present a plausible account of Japan's reluctant, prescient, warrior.
Unlike Tora Tora Tora! there is relatively little direct action, which is a good thing because the CGI is not entirely successful (the warships and aircraft look fine but the explosions look artificial), and in any case the political and military intrigues, social context and domestic background are much more interesting. It does present a rather flattering and one-sided view of Yamamoto - he always seems to be right in a decent and humane way. However, it is impossible to discern from such a film just how good his naval tactics were and these things are highly complex and still controversial. We get a few insights into his family life but I understand from Wikipedia he was a big patron of geisha (there is no reference to this in the film).
There are some stirring moments of self sacrifice for a Japanese domestic audience but the obvious and powerful message is what a terrible mistake the whole bloody affair was. I found the inevitable end very tense and moving. SPOILER ALERT- if you know nothing about the Admiral! - ironically he met his fate in one of the long range but lightly armoured aircraft that he championed so strongly.
This was an engrossing film that has stuck in my mind and I will probably watch again soon.