So, take this for whatever it's worth, but... I was not all that impressed.
Let me begin with a few praises. The first hour's special effects were well done (I feel differently about the last 60% of the film, but, I'll get there...). Set design and costuming were good. The female lead, Minami Hamabe (who played Noriko) was very good, and Hidetaka Yoshioka was goofily winning as "Doc" / Noda. I appreciated seeing the immediate effects of (losing a) war on a population, the devastation, poverty, poor health, disillusionment, and loss of purpose that the people of Japan experienced following the surrender of their Government... I could honestly watch an entire movie just about that, and about how within 20 years Japan went from ruined and dispirited former Empire to world-leading technology innovator and economic powerhouse (bettering, even, Japan's meteoric rise from feudal to industrial and global military powerhouse over the half-century prior to World War II). I was also surprised -- not always, pleasantly or comfortably -- to see so much political commentary in the film: Particularly, criticism of Japan's Government (both pre- and post-surrender), its restrictions on public opinion and discourse, its management of information and suppression of knowledge, its lack of patriotic or sacrificial fervor, and its perspectives on the value of human life (especially, vis-a-vis kamikaze culture). It's clear that, with its (frankly, reality-stretching) focus on CITIZEN defense and heroism, the filmmakers are no supporters of Japan's military at ANY point in its recent history. There are also subtle but definite criticisms levied at the hand-waving detachment of conquering American forces, postwar: At the same time as the film seems to chafe at U.S. oversight of pacifist surrendered Japan, it complains that the Americans leave too much to "local" control and resolution, which is baldly contradictory. All of this makes for an interesting, if inconsistent and undisciplined, narrative.
...Much of the rest of what I have to say is not terribly complimentary. The main character, Kōichi, a failed kamikaze and all-around coward, is unlikable-to-despicable, and the actor who portrays him, Ryunosuke Kamiki, is utterly unable to make him sympathetic, no matter how many times he shrieks like a girl and bashes his head against tables and floors in apologetic atonement that comes across much more like adolescent sado-masochism. His "redemption" arc is both obvious and clumsily portrayed, and the events of the last ten minutes negate it entirely. None of his relationships -- not with his disappointed and ignored love interest, not with his adopted daughter(...ish), not with his motley crew, and, especially, not with his apparently awestruck teenaged colleague (whose name I could not be bothered to note or remember) -- make any sense whatsoever; only his parents' now-childless and, apparently, widowed neighbor Ōta, who dismisses the returning Kōichi as a spineless, useless, worthless deserter (which he is), rings true, and seems deserved.
There are plenty of historical inaccuracies, as well, and they grate: Japan possessed no "jet fighters" in World War II, and Kōichi would not have known what one was by 1947. Nor had the nuclear arms race begun by 1947 or '48, so the constant allusions to MAD and U.S.-Soviet nuclear brinksmanship were equally ludicrous. Finally, not one American soldier appears onscreen, which would have been IMPOSSIBLE in postwar, occupied Japan.
As I alluded to, above, the early effects work is decent -- predictable shots of Godzilla, for example, diving beneath large naval vessels are well-done, and there are several sequences right out of "Jaws" that, while hardly innovative, are effective; and a VERY early action scene, surprising in its timing and ferocity, is easily the best such in the entire film. However, the way "Godzilla Minus One" retcons the creature's origin story is... bizarre. While American nuclear detonations in the Pacific do factor in to the "Minus One" storyline (which is supposed to serve as a prequel to the ORIGINAL Toho film, "Godzilla"), ultimate responsibility for its nature and destructive power is now shunted somewhat onto unmolested nature, itself, which undermines the entire power of the character and franchise. I frankly prefer Legendary's modern take, that Godzilla and his kin (and rivals) are ancient Titans, newly released from their epochal slumber to torment a newly radioactive surface world.
And, the latter half(-plus) of the film's special effects are... well, not all that special. While the creature's atomic "heat ray" is well done, his dorsal plates are... Well, ridiculous, as is his super-healing power, which reminds me of JJ Abrams' magic Tribble juice. (Yes, this is nitpicking, but fans of Godzilla are, well, discerning.
) The ultimate battle between the ragtag Japanese navy and The King of All Monsters is similarly ludicrous, and again owes much to Spielberg's infinitely superior shark movie....I really came into this film with enthusiasm; "Shin Godzilla" was quite good, and I enjoyed the first two Monsterverse entries, 2014's "Godzilla" and its immediate sequel. "Godzilla Minus One" had high aspirations, and it did manage to grab onto one or two innovative rungs, but it ultimately falls from the ladder of its own ambition. 6.6 / 10
ETA: While, overall, the original music used in "Godzilla Minus One" (by composer Naoki Satō) is very well done, more "classic" "Godzilla" themes by original franchise luminary Akira Ifukube appear, and while you might THINK they would be welcome, they are, in actuality, jarring and discordant.
