It's a fairly normal kaijuu film (i.e. amusing in bits, but basically boring). What's really unpleasant is the story of how this film happened.
A problem for shitty regimes is that people want to leave. After the Korean War (1950-53), North Korea became a dictatorship that grotesquely sealed itself off from the world. They can and do execute their citizens in public for crimes like political dissidence, defection, unauthorised religion and consumption of media not approved by the government. At the same time, though, they wanted to be strong and rich. They needed skills that just couldn't exist under their medieval regime, so they found an imaginative solution.
They kidnapped foreigners.
Most of those are South Korean. The total number is guessed at 3,800, with nearly 500 still in captivity there. Some of those will have been taken in the 1950s or 1960s. (North Korea has never admitted to this. They claim that all missing South Koreans are defectors who remain of their own free will, despite communication with relatives in the South being banned.)
However, North Korea also kidnapped probably hundreds of Japanese people. (They admitted to a certain number in 2002.) They took people from Malaysia, Thailand, Romanian, France, Lebanon and other places. There's a suspected American abductee. They'd do this for espionage, to acquire teachers on language and local customs, to brainwash, to use as spouses or sometimes just to eliminate witnesses.
In 1978, they kidnapped a famous film director (Shin Sang-ok) and his wife (Choi Eun-hee). Kim Jong-il was a huge movie fan, you see. He's a co-producer on this film. He could see that North Korean films were all rubbish, so he decided to fix that. This film is the last North Korean one Shin Sang-ok made before escaping to a US embassy in 1986.
Jesus fucking Christ.
I'll talk about unimportant things now, i.e. the film.
Mostly, it's a tale of noble peasants rebelling against an evil, oppressive government. I'm amazed that Shin managed to get this past Kim Jong-il, but maybe it was officially deemed anti-capitalist propaganda. Uh-huh. Yeah, right. You can tell that Koreans have a Confucian reverence for the elderly, because the baddies imprison our heroes' elderly father without food and torture the mother for information she doesn't know. They both die.
(Almost all named characters die in this film, in fact, whether they're bad or good. If they're bad, it's deserved. If they're good, it's tragic. Welcome to the Korean peninsula. South Korean cinema's also as dark as hell, for what it's worth.)
The film's first twenty minutes is stuff like this. We also have a peasant bandit hero (with gorgeous hair), plus his beautiful sister (hair normal). It's all very historical, shouty and serious, with lots and lots of extras.
After that, though, the sister pricks her finger and drips a slightly implausible amount of blood on to a tiny model Godzilla... sorry, uh, Pulgasari. (P/Bulgasari is an iron-eating monster from Korean mythology, but more importantly Kim Jong-il loved Godzilla films and this is specifically inspired by The Return of Godzilla. They even tricked the Godzilla effects team at Toho into working on it.) This little thumb-sized Pulgasari starts waddling and eating pins.
The audience falls about laughing. It's adorable! It also makes cute noises. It remains lovable even as it grows bigger.
What follows is mostly what you're expecting. Rebel rebel fight win death. "How can we defeat these rebels?" "I know a general!" Huge battle scenes with tons of extras, ballistas, catapulted flaming rocks, etc. Bloke gets hanged. Sometimes there's also a giant Pulgasari. It's amusing, but in a way that keeps you watching the clock. One interesting thing, though, is that the baddies keep finding new ideas to defeat Pulgasari and are way more imaginative in this respect than the military in real Godzilla films, despite being feudal warlords whose idea of high technology is "iron".
I woke up for the last ten minutes, though. The baddies have been defeated, i.e. no more battle scenes. Instead, our heroes have the problem that their saviour, Pulgasari, still needs to eat. He's a nice monster. He sacrificed himself to save the sister. However if he eats everyone's pots and farming equipment, they'll starve to death.
This is a typically dull kaijuu/battle/etc. movie with ten minutes of good scenes with Pulgasari and the sister. However, it's quite interesting thematically. Godzilla represents the nuclear bomb, but Pulgasari is the opposite. He eats weapons. Both he and the government need iron and will happily ransack villages to get it, but the government wants it to make swords and spears. Pulgasari eats them. After that, the sister's final big speech is about the possibility that Pulgasari's iron-eating could make weapons even more valuable and set the world at war. "That you, our saviour, could be our enemy!"
In short, he's a benevolent, pacifist Godzilla. He's into unilateral disarmament and is willing to topple the government to get it, with his tragedy being that this might not work if you look on a global scale.
If you like Godzilla films, by all means try this. It seems fairly normal by genre standards to me. If nothing else, you'll be able to wonder what happens when Pulgasari goes to the toilet. (Also, the sister gets past guards by posing as a whore.) Pulgasari himself is cute and amusing. There's also a 1996 American remake called Galgameth, directed by Sean McNamara and written by Shin Sang-ok himself.