This movie is not the movie to see for an epic fight between the two legendary monsters. It's a movie to see for all the fans of badly executed special effects in the true spirit of 50's scifi b-movies. In that respect, it's a true classic. If you enjoyed the Beasty Boys' video for "Intergalactic Planetary", you'd love this movie as a Japanese feature length counterpart. They've got the same quality feel to them, and the same incredible special effects - and here, "incredible" is meant literally.
Some of the highlights of this movie for me: the toy plane a little boy sees hanging in a toystore and makes him stop because he badly wants it, is the same plane that flew in formation attacking Godzilla. And by that I don't mean the same type of plane, but it's the exact same plastic model! Also, true to the original story, King Kong comes from a tropical island. As we all know, the cliché has it such an island is inhabited by black people wearing banana-leaf skirts and toting spears. This being a Japanese production, the natives are played by Japanese, painted black and given curly wigs...
So if you enjoy laughing at the ridiculous details in movies, love to see fights between people wearing halloween suits trying to make it look like the real thing, with some mediocre fireworks in between, you have to see this movie. If you're looking for a credible classic, such as the original King Kong movie, or high-tech special effects and stunning visuals, this is not the one for you ;)