I really wanted to like this movie. It got couple thumbs up from Reason stalwarts Peter Suderman and Eric Boehm. They (understandably) were attracted to the movie's libertarian subtext. On the other hand, I found it to be a literal snoozefest; I kept falling asleep and missing long swaths of the narrative.
The Zilla-effects are impressive (also Oscar-winning) and they are kept at a below-overkill level. When the beast throws around naval warships and commuter trains, my inner 13-year-old couldn't help but go "Whoa!". The carnage is spectacular; when a post-attack news report puts the casualties in a small city at 30,000, I said "That few?"
But the plot: things kick off when Shikishima, our hero, a kamikaze pilot at the end of WW2, flies to the small island of Odo, complaining to the support crew there of his plane's mechanical failure. This fools nobody; Shikishima has made the sensible, but dishonorable, choice to not sacrifice his life in a futile gesture of loyalty to Japan.
Unfortunately, Odo is also the home to that big titular lizard; he's a youngster, but still very destructive. During the fight, Shikishima is ordered to get into his plane and fire its guns at the beast. Similarly to the kamikaze mission, he realizes this would be (a) futile and (b) suicidal, so he bails. And is one of the only survivors.
A guilt-filled, disgraced Shikishima returns to a postwar Japan in ruins. He acquires a makeshift family of sorts, and ekes out a living clearing mines from the waters around Honshu. But (apparently) A-bomb tests have put Mr. G. Z. on a growth spurt, and made him even more homicidal. So their paths are destined to cross again. Will Shikishima redeem himself? Not without a lot of overacting, unfortunately.
Libertarians like that the final battle is carried out by a semi-private force of volunteers. I was somewhat surprised at how cynical the movie was toward the Japanese government. (For example, a character observes "Come to think of it this country has treated life far too cheaply.") The US bombed the country into rubble, some of it radioactive, but … fine.
Netflix has the option to either watch with original Japanese or dubbed English dialog. I recommend the former; some of the dialog is pretty stupid and overwrought, and you only have to read it, not listen to it too.