I had a fear that the character of Arthur would become a monotonous bore, but he didn't. Dudley Moore doesn't just play possibly one of the best drunk performances; he gives humanity to it. I feel like this movie set the standard to the many man-child comedies that would later come. However, as great as Dudley Moore is, John Gielgud is greater. He stole every scene he was in and Minnelli plays off him well.
Steve Gordon's tight, hilarious and heartfelt screenplay looks even better 30 years later with its brilliant comic turns by Dudley Moore and John Gielgud and a talented supporting cast backing them up. http://eddieonfilm.blogspot.com/2010/07/he-did-more-than-just-think-funny.html