His frankly erotic images caused much agitation about the funding of the arts. Many conservative and religious organizations opposing public funding used his images as a means of shocking people.
Most of his photographs he made in studio. His most apparent themes are Portaits of (now) famous people, S&M, mostly male nudity and flowers. His specialty was considering his photography equal to paintings, and so giving them quite exotic framing and printing. He did indeed live in a time when photography was just being accepted as one of real arts.
He was a great networker, never losing a chance to promote his work, and never failing to invite all his acquaintances to his gallery openings.
Robert Mapplethorpe died of AIDS.
Suggested reading: Patricia Morrisroe: Robert Mapplethorpe: A Biography
See also: The erotic male in photography