I've watched the SRS Blu-ray release of this "lost classic" and I have to say that it's not bad. Not great mind you, and I think it's supposed to be something of a comedy in tone. The physical effects are good with excellent miniature work, and the monster is remarkably unique in it's look. What's really impressive is the quality of the movie itself. Really sharp and crisp, making the black and white film easy to watch.
The plot is very basic, aliens drop a monster on earth to test it's defenses. None of the characters have any depth to them, and there are times that the monster attack is background for comedic escapades by them.
It's worth a watch, especially if your a kaiju completist. But just don't expect anything extraordinary or mind blowing. This was obviously made more for laughs for a Korean audience, and not as competition for the Toho kaiju juggernaut.