If you look in the right places, a lot has been said about this 1956 film, from extrapolating the cortisone dependence to drug use, and highlighting the dark underbelly of middle class complacent consumerist society of 50's America...some of which is true, although the extent of these discussions - even detailed dialog about the metaphors of the posters that hang in the protagonist's home - sometimes stretches credulity; there is such a thing as reading too much into a movie. Thankfully Bigger Than Life works even without its metaphors.
By showing us the likability of Mason's character in the first act (apparently brought in by extensive script rewrites from Ray and Mason) the film makes his transformation into a self absorbed tyrant more palpable. We can see how his suppressed worries and insecurities erupt into irrational actions when he can no longer think straight. Yes it's a little formulaic, but that's inherent in the film's structure and works well enough. Mason's performance with its attention commanding air is the strongest element that hold this picture together. The film is also notable for its very ingenious use of scope photography (Joe MacDonald) in a mostly indoors set drama play. The view is always interesting without getting gimmicky.
Caveats? Well, I thought Mason's wife's character (Barbara Rush) was a little under-done. She appears too submissive to her husband's manic whims, even when her own son suffers for the same, and her practical decision making ability varies as per the script's demands. Also the biblical element that forms the films climax seems to come on from, even for Mason's delusions, a little too far off. But these are lesser quibbles for what is still an interesting watch with a major league acting performance from the great James Mason.