Ideas interpreted on a scale different from the one in which they were conceived frequently accumulate new meaning along the way. Huston's rescaling—you might call it "cinematizing"—of [The Night of the Iguana] results in a reduction of meaning, yet sometimes the results are surprisingly beneficial. Listening to the protagonists reel off accounts of their spiritual difficulties and arrive verbosely at poetic solutions to them, it becomes patently clear that [Tennessee] Williams' thinking is no longer abreast of the times…. Williams has fallen behind, has been overtaken by America, and Huston's reinterpretation, whether by deliberate deflation or plain vulgarization, often acts to soften the blow.
Watching The Night of the Iguana as Huston's film rather than Williams' play—which is not quite impossible—other difficulties arise. Half the time the dialogue appears wholly unrelated to the action; one or the other is more often than not superfluous, and both together are excessive. It is like watching one ball game on television and listening to another on the radio: you need two minds to follow the action. Huston has simply failed to find the images necessary to maintain coherence. The talk and cinematography move at different speeds, and the effect can be dizzying. (pp. 51-2)
[Credibility] is the central problem of The Night of the Iguana. Its principal theme is the state of being at the end of one's tether, as frequent cuts to an iguana at the end of its tether repeatedly remind us. Whatever power the stage version had was mustered by dint of rhetoric, the gathering force of anguished oratory. But Huston, as good as he is with mise-enscène, is most at home in films that are laconic, verbally thrifty. Consequently, for lack of imagery to support all the talk, the credibility of the action collapses. Williams' thunder erupts, has its moments, but ultimately disintegrates into the clatter of tin cans. What makes this all so unfortunate is that there is a lot of nascent good in the film, though in the end it has to be placed alongside the thousands of other movies which afford evidence that seeing is by no means believing. (p. 52)
Stephen Taylor, "Film Reviews: 'The Night of the Iguana'," in Film Quarterly (copyright 1964 by The Regents of the University of California; reprinted by permission of the University of California Press), Vol. XVIII, No. 2, Winter, 1964, pp. 50-2.