You'll notice something when you go to Lumet's IMdB page. Lumet's filmography is filled with what many would regard as flops. It should be no secret that the man who directed such masterpieces as Dog Day Afternoon, Network, and Serpico was also responsible for movies like The Wiz, Gloria, and Family Business. Lumet did not ignore them as critical failures in the least, however. He accepted them, refused to regret them, and continued on making the projects that he found enticing and worth his while. Sidney Lumet was not afraid of critical backlash; he was a director who found the challenge of making any sort of movie, whether it be dramatic or comedic (or even musical) a worthwhile endeavor. He had no interest in delegating himself to one specific genre and cranking out the same old hat trick time after time. To put it frankly, Lumet was a director with balls. He also was not stuck on the idea that great movies can only be made with film. Like contemporary director David Fincher, Lumet used the digital process for his final movie Before the Devil Knows You're Dead. The trivia portion of the movie on its IMdB page states: "Sidney Lumet was introduced to digital film techniques through this production and reportedly loved working with digital film, primarily due to it's convenience. This was his first and ultimately only film to be shot in the digital format." Lumet was open to any technological advances in the cinematic world, constantly seeking to challenge himself as an artist.
"Sidney Lumet was one of the greatest directors in the long history of film. Compelling stories and unforgettable performances were his strong suit." - Steven Spielberg