Calling Stevie Smith's Not Waving but Drowning "the best collection of new poems to appear in 1957," Poetry contributor David Wright observed that "as one of the most original women poets now writing [Stevie Smith] seems to have missed most of the public accolades bestowed by critics and anthologists. One reason may be that not only does she belong to no 'school'—whether real or invented as they usually are—but her work is so completely different from anyone else's that it is all but impossible to discuss her poems in relation to those of her contemporaries." "Without identifying itself with any particular school of modern poetics," Linda Rahm Hallett similarly noted in the Dictionary of Literary Biography, "[Smith's] voice is nevertheless very much that of what she once called the 'age of unrest' through which she lived." Combining a deceptively simple form and mannered language with serious themes, Smith was able "both to compass the pity and terror of her themes and to respond to them with rueful courage and humour," a Times Literary Supplement reviewer remarked.
Smith's "seemingly light verse," stated Hallett, contains a "sometimes disconcerting mixture of wit and seriousness ..., making her at once one of the most consistent and most elusive of poets." "We say that her poetry is childlike, everyone is charmed, delighted," Jerome McGann explained in Poetry. "She goes self-consciously to Blake, to nursery rhymes, to naive ballad forms, and offers us afterwards imaginary gardens with real toads in them." Smith's writings, however, frequently demonstrated a fascination with death and also explored "the mysterious, rather sinister reality which lurks behind appealing or innocent appearances," Hallett described. As a result, Wright commented, "the apparent geniality of many of her poems is in fact more frightening than the solemn keening and sentimental despair of other poets, for it is based on a clear-sighted acceptance, by a mind neither obtuse nor unimaginative, but sharp and serious, innocent but far from naive, and because feminine having a bias towards life and survival, of the facts as they are and the world as it is."
Contributing to the deceptive quality of the poet's work was her language, which the Times Literary Supplement reviewer termed "Smith's most distinctive achievement." The critic elaborated: "The cliches, the excesses, the crabbed formalities of this speech are given weight by the chillingly amusing or disquieting elements; by the sense of a refined, ironic unhappiness underlying the poems; and by the variety of topics embraced by the poet's three or four basic and serious themes." Although the writer found some of Smith's work "indulgent, even trivial ... it ought at last to be recognized that Miss Smith's is a purposeful and substantial talent. From below the surface oddness, her personal voice comes out to us as something questing, discomfiting, compassionate." Smith's "highly individualistic poetic style [was] vulnerable to shifts in critical taste and to the charges of eccentricity, a charge which Smith risked, and in a sense even flirted with, throughout her career," Hallett concluded. "However, the integrity with which she adhered to her own style earned Stevie Smith a considerable amount of respect, and, more than ten years after her death, her reputation with both readers and fellow poets is deservedly high."