Ah yes...the 70s, when everyone KNEW that the future was going to look like one big disco! Seriously, though, although not as sleek as modern sci-fi, it comes across today as almost bootleg quality sci-fi from a quasi-subversive countercultural group...which may, actually, help the film's credibility. If nothing else, it provides some interesting fodder for discussion on ethics, the role of the state in society, human rights and collective versus individual good. Which is often what good science fiction is supposed to do, right?
(P.S. - also the culture of youth, hedonism, environmentalism [how far is too far in preserving resources] and the dynamics of religion [the buy-in to "Caroussel" serves a pseudo-religious function, allowing people to ignore the specter of their own mortality by a belief that a higher - in this case technological - power that can provide them with another life])