What is it that makes Orson Welles such a great filmmaker?

What is it that makes Orson Welles such a great filmmaker?
The Word "Great" is debatable. And as I doubt any renown Film Makers are in the house, and as only a Film Maker would know, as "It takes one to know one" for Example, no one could judge a Musical Recital, without knowing Music, such as composition, harmony, scales, pitch, etc. when you say this band or that band is Great. or that film or this film is Great, it's purely a matter of what gives YOU Pleasure, or inspiration. But as for What makes a"Great Film Maker" you are talking about what technicaly it takes., and of course that would be Experience. here is a brief article I found on the web, as you will see, he was somewhat a failure at first, not Great at all according to the article:His first film to be seen by the public was Citizen Kane (1941), a commercial failure losing RKO $150,000, but regarded by many as the best film ever made. Many of his next films were commercial failures and he exiled himself to Europe in 1948. In 1956 he directed Touch of Evil (1958); it failed in the U.S. but won a prize at the 1958 Brussels World's Fair. In 1975, in spite of all his box-office failures, he received the American Film Institute's Lifetime Achievement Award, and in 1984 the Directors Guild of America awarded him its highest honor, the D.W. Griffith Award. His reputation as a film maker has climbed steadily ever since.So you tell me,,what makes him such a Great Film Maker?