Giant from the Unknown (1958) is rather a cheap and pedestrian sci fi film with an absurd premise, lots of "stuff" happening, rather unconvincing acting, somewhat dull dialogue and a largely unimpressive "monster' character. Still, it must be said that it's perfect viewing fare for a rainy afternoon!
As far as film monsters go, Vargas seems to be pretty lame. One could say that he is a monster in a moral rather than in a scary physical sense. He is described as being depraved and brutal and has remained so even after three and a half centuries of suspended animation.
The film does suffer from continuity and subplot development problems. For instance, we are never quite sure why Parker and Wayne don't like each other. What is the history behind their animosity? They just seem to detest the sight of each other.
Giant from the Unknown does contain moments of good pacing, and combines some effective creation of eerie atmosphere, and black and white cinematography. In addition, the 77 minute running time doesn't allow the film to drag too much and Albert Glasser's orchestral score is quite solid and powerful.