Summary from Wikipedia

Early in his career, he was a successful painter of architectural decorations in a conventional manner. As he began to develop a more personal style, his work was the subject of controversy that culminated when the paintings he completed around 1900 for the ceiling of the Great Hall of the University of Vienna were criticized as pornographic. He subsequently accepted no more public commissions, but achieved a new success with the paintings of his "golden phase", many of which include gold leaf. Klimt's work was an important influence on his younger peer Egon Schiele.