A pre-Godzilla, and so pre-Kaiju film from Honda. Honda's main draw has always been his miniature work, which still comes in handy when doing a war flick. Without the Kaiju cheese though, it's not really the same thing. Eagle of the Pacific is a more serious take on the Pearl Harbor attack.
Yamamoto is a tactical genius and loyal to the emperor of Japan. That puts him in an awkward position, as he is ordered to lead the attack on Pearl Harbor, a mission he opposes. Yamamoto is overruled, so even though he feels the mission should be aborted, he'll do his best to make it work.
The first hour is pretty slow, it isn't until the second half that the war scenes introduce some much-needed action. With people like Mifune and Shimura on board this was certainly not an inconspicuous project, though it's not a film that really stands out as majestic nowadays. I'm not surprised Honda took a different path after this.