The finale of the Weissmuller Tarzan movies is a rather weak one. There are a few things that derail this film.
First, Tarzan spends much of the film wearing floppy sandals. In my opinion, any footwear on Tarzan, whether it be sandals or boots as sometimes portrayed, takes away from the character, which is supposed to be anti-civilization and pro-jungle.
Second, the character of Benji, as mentioned in a previous post, totally derails the movie as the comic foil. To me, his character is unnecessary to the film's plot.
Also, while Weissmuller still cuts a commanding figure as Tarzan, it's apparent that he was not in his best shape. Although in his later Jungle Jim movies, his physique had improved somewhat from this film.
The octopus battle is a terrific idea, but I think it should have been done in an earlier Weissmuller film when he was at his physical peak. Likewise, the battle, which takes only 30 seconds tops, would be much more thrilling if it was drawn out to 90 seconds to 2 minutes like the classic giant crocodile battle in Tarzan and His Mate.
And while Brenda Joyce as Jane and Linda Christian as Mara are overwhelmingly pleasing to the eye, it doesn't manage to salvage this last Weissmuller film - a disappointing ending to a great character run.