Is this an exaggerated concept? I don't believe so. I find this concept great and very realistic. We mention in the movie that the machine bases its calculation on only one element. Obviously, we should have encountered a man-fly as soon as the teleportation was finished, but the idea is still there.
This movie is a wink to those suffering of fatal diseases. In my opinion, there is no greater fear than fear of yourself and The Fly discusses the subject. At first, Seth, the researcher, seems to be in great shape: he is agile, strong and full of energy. But as time passes, he becomes evil, impatient and loses parts of his body. Every time he vomits or decomposes, we explicitly see the scene and the evolution of his transformation. This film is violent and it is a realistic violence that sends shivers down our backs.
The actors are superb and brilliantly illustrate the psychological aspect behind the troubles in their love relationship they live because of the transformation.