IT would be difficult to describe Martin Scorsese's fine new film, ''The King of Comedy,'' as an absolute joy. It's very funny, and it ends on a high note that was, for me, both a total surprise and completely satisfying. Yet it's also bristly, sometimes manic to the edge of lunacy and, along the way, terrifying. It's not an absolute joy by a long shot but, in the way of a film that uses all of its talents to their fullest, it's exhilarating.
''The King of Comedy,'' which opens today at the Coronet, is most easily categorized as satire. Though television and instant celebrity are two of its principal targets, it has less in common with something like Paddy Chayefsky's ''Network'' than with Susan Seidelman's ''Smithereens.''
Like Wren, the aggressive groupie in ''Smithereens,'' Rupert Pupkin, the hero of ''The King of Comedy,'' wants to be celebrated and famous. However, unlike Wren, who has no talent for anything and knows it, Rupert is convinced that he is a great comedian, nothing less than ''the king of comedy,'' which is what he calls himself.
As played by Robert De Niro, in one of the best, most complex and most flamboyant performances of his career, Rupert Pupkin represents the apotheosis of all that is most commonplace in America's increasingly homogenized society. For Rupert, immortality is a series of boffo one-liners.
Though there is a little bit of almost every film Mr. Scorsese has ever made in ''The King of Comedy,'' including even ''Taxi Driver'' and ''Raging Bull,'' this new work is an original. Its excellent screenplay, written by Paul D. Zimmerman, a former film critic for Newsweek, is witty and, even in Rupert's hilarious fantasy sequences, tough. Like all good movies, the film has the measure of the times that produced it.
When we first meet Rupert Pupkin, there is little to distinguish him from all of the other pushy, half-crazed, love-sick fans who wait for their idols outside stage doors, furiously demanding autographs and as likely to turn vicious as they are to swoon with ecstasy at the merest brush with celebrity. Rupert's idol is Jerry Langford, a late-night, television talk-show host played - with brilliant solemnity - by Jerry Lewis. ''The Jerry Langford Show'' is obviously modeled on Johnny Carson's, but the Langford character and wellcorseted figure suggest the off-stage Bob Hope.
Rupert pursues the defenseless Jerry Langford with the singleminded intensity of the true psychotic. When all other avenues to the achievement of his goal - a 10-minute guest spot on ''The Jerry Langford Show'' -fail, Rupert and his equally obsessed sidekick, Masha (Sandra Bernhard), a rich groupie with an East Side mansion, decide to kidnap Jerry and to hold him for one of the weirdest ransoms in the history of narrative films.
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One of the ways in which ''The King of Comedy'' works so effectively is in the viewer's uncertainty whether it's going to wind up as terrifyingly as is always possible. It's full of laughs, but under all of the comic situations is the awful suspicion that our laughter is going to be turned against us, like a gun.
Mr. Zimmerman's screenplay is ungraciously hilarious when it focuses its attention on pure show biz, as when, in one of Rupert's fantasies, he attempts, with the gravity of a Barbara Walters, to explain the sources of his comic routines. I also cherish its throwaway lines: Rupert, lying in wait for Jerry Langford in a fancy network waiting room, keeps staring at the ceiling. ''Is it cork?'' he asks, being suave. Says the bored receptionist: ''I don't know. Is it dripping on you?''
Though the film is Mr. De Niro's from start to finish, all of the members of the cast are impeccable, including Mr. Lewis, Miss Bernhard, who is new to films and may be one of the decade's comic finds; Diahnne Abbott, as Rupert's skeptical, sometime girlfriend; Catherine Scorsese (the director's mother), as Rupert's mother, who remains a quarrelsome, off-screen voice throughout; Shelley Hack, as the sort of beautiful, cool network secretary who could give lessons in the art of the elegant put-down. Among the real-life personalities who turn up as themselves are Tony Randall, Victor Borge and Dr. Joyce Brothers, who doesn't seem to have any idea that, under these circumstances, she's a not-very-kind joke.
-Vincent Canby, The New York Times, 1983