The ghastly black and white of Gattaca and the totally soulless atmosphere of the place is a omnipresent threat to Vincent's passionate dreams and fears. Finally, blue in the last swimming sequence suggests heavenly help, a dark night of the soul that meets God before He brings the dawn. Furthermore, Vincent recalls Vincent Van Gogh, obsessed with visions that no one else could appreciate. And as Jerome becomes Eugene, he weeps less for himself, and sees a purpose finally in his life. This is science-fiction without special effects to speak of.
Sets are simple, and deliberately unrealistic, to put maximum emphasis on character.
I find it reminiscent of the best of the greatest written science-fiction by sensitive authors such as Ray Bradbury and Orson Scott Card, a journey into the future about the full human condition, including the spirit. How sad this kind of science fiction almost never makes it to the screen.