Steamboat Willie was the main source of income for Walt to make other productions with Mickey Mouse and other characters. He latched onto the hearts of his audience and was immediately a hit in the animation business.
The first full-length film Disney ever created with dual sound and animated images was Fantasia; everyone remembers watching this film and making Mickey say things even though there was not any words. Not only did he successfully add stereophonic sound to Fantasia, he also used storyboards, optical printers and multiplane cameras to heighten the story and characters. If you take a look at some of the first animations, such as Émile Cohl's Fantasmagorie in 1908, and compare them too Walt's animations there is prime differences that show how much more experienced Walt's films looked. He created an enhanced and detailed animation that made the eyes of families all over the place watch in awe. The cartoons let the imaginations of many run wild, even when there wasn't any sound included. As soon as sound hit the theaters there were even more people flocking there. You can imagine what happened when Disney's films started adding color.
Disney, after he moved to California for better opportunities, made an agreement with United Artists, an entertainment studio, to try out a film with Technicolor. His agreement was to make only one film to see how the audience would react and to make a black and white version too just in case they freak out. The film was Silly Symphony Flowers and Trees in 1932 and was a bigger hit than Disney expected. Bob Thomas, a Hollywood reporter, wrote a book on Disney, Walt Disney: An American Original, and in it he said, "After the first few scenes had been completed (in color on Flowers and Trees), Walt showed them to a friend, Rob Wagner, publisher of a literary magazine in Beverly Hills (Script magazine). Wagner was so impressed that he invited Sid Grauman, impresario of Grauman's Chinese Theater to see the film" ("Disney and Early Technicolor").