Monster Zero,to give this film it's most common name,is another quality Godzilla film coming on the heels of the classic Godzilla Vs Mothra and Ghidorah the 3 Headed Monster. The film is a slight notch down from those two,but still a hugely entertaining movie-inventive,exciting and quite spectacular considering it's comparatively low budget.
The film combines the monster battle plots of the previous films with an alien invasion story a la Battle In Outer Space. The idea of aliens controlling monsters to attack Earth would later be done to death in later series entries. The plot here is quite clever and interesting,although the film is a little slow and only really gets going in the final third,which has one of the best destruction scenes of the series {although spot the tiny bit of footage from the films Rodan and Mothra}. Not enough of the monsters is seen in this film,and the two battles are too brief,despite the priceless sight of Godzilla's victory shuffle.
Nevertheless,there is much to enjoy,including Nick Adam's VERY enthusiastic performance and some of his silly but cool dialogue,some very impressive special effects and visuals {one day people will stop saying the effects in these films are poor},and a rather daring alien/human romance that even includes sex, {although you'll have to listen for the reference}. The US version only had minor cuts and music cue alterations,nothing to ruin the film.