Sexton is seen as the modern model of the confessional poet. Maxine Kumin described Sexton's work: ""She wrote openly about menstruation, abortion, masturbation, incest, adultery, and drug addiction at a time when the proprieties embraced none of these as proper topics for poetry."  Sexton's work towards the end of the sixties has been criticized as "preening, lazy and flip" by otherwise respectful critics. Some critics regard her dependence on alcohol as compromising her last work. However, other critics see Sexton as a poet whose writing matured over time. "Starting as a relatively conventional writer, she learned to roughen up her line. . . . to use as an instrument against the 'politesse' of language, politics, religion [and] sex."
Her eighth collection of poetry is entitled The Awful Rowing Toward God. The title came from her meeting with a Roman Catholic priest who, although unwilling to administer last rites, told her "God is in your typewriter." This gave the poet the desire and willpower to continue living and writing. The Awful Rowing Toward God and The Death Notebooks are among her final works, and both center on the theme of dying.
Her work started out as being about herself, however as her career progressed she made periodic attempts to reach outside the realm of her own life for poetic themes. Transformations (1971), which is a revisionary re-telling of Grimm's Fairy Tales, is one such book. (Transformations was used as the libretto for the 1973 opera of the same name by American composer Conrad Susa.) Later she used Christopher Smart's Jubilate Agno and the Bible as the basis for some of her work.
Much has been made of the tangled threads of her writing, her life and her depression, much in the same way as with Sylvia Plath's suicide in 1963. Robert Lowell, Adrienne Rich and Denise Levertov commented in separate obituaries on the role of creativity in Sexton's death. Levertov says, "We who are alive must make clear, as she could not, the distinction between creativity and self-destruction."