The Three Musketeers is full of action, dash, and slapstick, and it depressed me very much. This is Richard Lester's first picture since The Bed Sitting Room (1969), a picture that showed a sad lapse in Lester's judgment of scripts though not in his unique and wonderful filmic style. The Three Musketeers has a sounder script, but it shows an absolute abandonment of the style that made Lester Lester. Such films as A Hard Day's Night and The Knack and How I Won the War overflow with imaginative pyrotechnics that manage to be brilliant and helpful at the same time. The Three Musketeers overflows with nothing but what must in Lester's case be called conventional ebullience. It tries to render the Dumas novel as action comedy and, if memory is serving, it takes that vein somewhat further than the Doublas Fairbanks version did. Here it's not only D'Artagnan who is a somewhat overheroic hero; virtually all the other characters except Richelieu are used for laughs, one way or another. But none of it is Lester comedy, cinematic eruption. Almost all of it is script-y, devised, derivative—and harmful to Dumas. (pp. 274-75)
The script, by George Macdonald Fraser, is a sequence of stunts and set pieces, rather than a strong sequential narrative. D'Artagnan and his three friends are stripped of character and become interchangeable brawlers—so Dumas is robbed of his nice touches of sentiment. And the conclusion is just a limp pageant….
It's one dragged-out forced laugh. No sweep, no romance, no convincing chivalric tradition to mock. And, worst of all, no Lester. Not the Lester who has been missing for too long. (p. 275)
Stanley Kauffmann, "'The Three Musketeers'" (originally published in The New Republic, Vol. 170, No. 17, April 27, 1974), in his Living Images: Film Comment and Criticism (reprinted by permission of Brandt & Brandt Literary Agents, Inc.; copyright © 1970, 1971, 1972, 1973, 1974, 1975 by Stanley Kauffmann), Harper & Row, Publishers, 1975, pp. 274-75.