[Lenny] is a mess—precisely because it is neither fact nor imaginative fiction. Fosse and Barry never figured out for themselves how this nothingy little comic grew into a heroic figure and, rightly or wrongly, a legend; they further becloud the issue with "arty" fragmentation and time shifts, so that past (the unknown, two-bit comedian), present (the phenomenally risen and fallen, one and only Lenny Bruce) and future (his mother, wife, and agent spinning out his myth in posthumous interviews with a heard but unseen journalist) are utterly scrambled, and we cannot even superficially follow the transitions, evolutionary and deteriorative, that marked the man's story.
The film makers were clearly hampered by the need to appease Bruce's widow and mother. But with a marvelous mother like the one on screen, no boy could have grown up troubled; and with a basically so loving husband-wife relationship, whence came the divorce, and all those marital and post-marital agonies?… The film's dishonesty is epitomized by the scene in which Bruce gets his wife to have sex with a lesbian as he watches and, eventually, joins in. The idea is to evoke moral deterioration, have a daring and salacious scene, and still not offend any moviegoers….
The fragmented structure, furthermore, prevents us from seeing the Bruce routines whole; the best ones, indeed, are absent altogether….
Most painful about this lackluster film are the bits of barbershop Freudianism in the posthumous interviews: "He had to prove it to himself."—"Insecurity?"—"Insecurity." (p. 44)
John Simon, "Films: 'Lenny'" (reprinted by permission of Wallace & Sheil Agency, Inc.; copyright © 1975 by John Simon), in Esquire, Vol. LXXXIII, No. 2, February, 1975, p. 44.