For people like me who were born long after the '60s ended, we can only learn about the era through cultural artifacts, of which "Hair" is one. This is certainly a well done tour de force. One can get a sense of how things were for the hippie culture. Probably the most impressive scene - for me at least - is when the group crashes the rich people's party. As for the movie's final scene, one might interpret it as the symbolic end of everything that the '60s represented.
But no matter how one interprets this movie, it's important to understand that even though the '60s themselves may have ended, the movements that typified them still exist in small enclaves. It's a time that people won't soon forget.
Anyway, this movie is one that I definitely recommend. Milos Forman scored another great one here, right between his two masterpieces "One Flew Over the Cuckoo's Nest" and "Ragtime" (so why did he later make a piece of crap like "Man on the Moon"?!). Starring John Savage, Treat Williams and Beverly D'Angelo.