This is a very odd giant monster movie about a hairy, ugly, ape-like beast that escapes from a research lab. Somehow, the beast has an evil twin. One of the monsters is green, the other one brown. One evil, one good. And we are reminded of that endlessly thoughput the movie. These two gargantua are the equivalent of brothers that are always beating each other up. I thought the monster fights were interesting in that they occurred with greater speed than the typical, lumbering giant monster approach in every other film of the time. The Gargantuas suits were very flexible, almost form-fitting compared to the usual. It gave the stuntmen the opportunity to accomplish some pretty impressive wrestling moves and to run at a decent clip. The miniature effects were also very impressive.
There are a couple of memorable moments including a neat shot of a gargantua underwater, glaring up at its future victim. There is also one of the worst songs and accompanying performances I have ever seen in a movie. Kipp Hamilton sings a pop song on the deck of a ship. The song is called "The Words Get Stuck in My Throat" or something crazy like that. And if that isn't bad enough, Hamilton's voice is absolutely awful.