"If we were to describe a man as deceitful, drunken, cowardly, dishonest, boastful, unscrupulous, gluttonous, vainglorious, lazy, avaricious, and selfish, we should hardly leave room in him for good qualities. No one would take it as a compliment to be described in this way, and we would avoid a person described in such a fashion. Falstaff was all those things, but probably no character in all literature is better loved. Only Don Quixote can compete; and our love of Falstaff is not despite his roguery but because of it."
Side note: More than one reviewer described Ignatius J. Reilly in A Confederacy of Dunces as "Falstaffian."
UPDATE for the curious: Theodore Dalrymple is is a British psychologist and writer well-known in some circles for his work with prisoners. Sir John Falstaff is a large and lazy knight made famous by William Shakespeare in three plays, most notably Henry IV, where he is the drinking buddy of Prince Hal (the future King Henry IV), In fairness, Henry IV did not have Kenneth Branagh reciting a stirring speech to his troops the way Henry V in the video above did, but Shakespeare wrote about both kings.