The Hollywood Reporter has republished their review for "King Kong vs Godzilla" by James Powers, originally published on June 6, 1963:
A funny monster picture? That's what Universal has in King Kong vs. Godzilla, a Japanese-made Toho production.
There are all the usual special effects characteristic of these films. The difference is that this one spoofs the whole cycle. Audiences which patronize this kind of picture will eat it up. It should be a big success via the multiple-booking, exploitation route.
Since the film was re-edited and some additional scenes made for the English-language edition, credits are mixed. John Beck produced the American version, and Thomas Montgomery directed it, after the Japanese original by Inoshiro Honda. Paul Mason and Bruce Howard did the English-language screenplay. Dubbing is good.
The plot simply is a device for getting the two celebrated monsters, King Kong and Godzilla, into conflict. They meet in Japan. Human efforts to divert or disable them having failed, a plan is devised for getting them together, on the theory they will knock each other off.
In a scene reminiscent of two gigantic TV wrestlers grappling for holds, the prehistoric beasts grunt, puff and ham it up for all the world like Gorgeous George and Man Mountain Dean. It's a peculiar kind of humor, but it does play.
Eiji Tsuburaya did the special effects, which are meticulous, as they always are in Japanese films of this sort. The cast is largely Japanese, with some American actors interpolated in scenes shot in this country.
Color is good, and other technical credits are also satisfactory.