[On Let's Get It On] Gaye uses his voice (in both lead and background) to create a dreamlike quality only slightly less surreal than he did on What's Goin' On, his very best record to date. But while on the earlier work he sang of the difference between his vision of God's will and man's life, he is currently preoccupied with matters purely secular—love and sex.
And yet he continues to transmit that same degree of intensity, sending out near cosmic overtones while eloquently phrasing the sometimes simplistic lyrics. But then that should come as no surprise from the man who sang "She makes my day a little brighter / My load a little bit lighter / She's a wonderful one," in a way that made it difficult to remember whether he was singing about God or woman—and whether he felt there was any difference….
Let's Get It On is as personal as What's Goin' On but lacks that album's series of highpoints. Instead, it ebbs and flows, occasionally threatening to spend itself on an insufficiency of ideas, but always retrieved, just in time, by Gaye's performance. From first note to last, he keeps pushing and shoving, and if he sometimes takes one step back for every two ahead, he gets there just the same—and with style and spirit to spare. (p. 74)
Jon Landau, in his review of "Let's Get It On," in Rolling Stone (by Straight Arrow Publishers, Inc. © 1973; all rights reserved; reprinted by permission), Issue 149, December 6, 1973, pp. 74, 76.