Critical reviews of Addonizio's fourth collection of poetry, What Is This Thing Called Love, were mixed. In Publishers Weekly, an anonymous reviewer states that the collection is written in a style that is "two parts confessional, one part standup comedy, and one part talking blues." The reviewer also notes that "Addonizio's in-your-face persona and her avoidance of technical difficulty should help her attract the wide audience she explicitly invites." A more favorable review of Addonizio's book was published in Booklist. The reviewer, Donna Seaman, claims that "Addonizio's poems are like swallows of cold, grassy white wine" in that they "go down easy and then, moments later, you feel the full weight of their impact." Seaman also observes that Addonizio's poems are "finely crafted and irreverent" as well as "timeless in their inquiries into love and mortality." According to Seaman, the poems are "rife with mystery and ambivalence, and [are] achingly eloquent in their study of the conflictful union of body and soul."
Diane Scharper's review of Love for Library Journal was less enthusiastic. Scharper compares Addonizio's collection to Anne Sexton's collection Love Poems (1969) and declares that Addonizio is "neither as sharpedged nor as passionate as Sexton." Rather, Addonizio's poems are "lukewarm and 'cool' at their best" and are best suited "for larger public libraries." William Logan's review in New Criterion was even more negative. In an article that is largely an attack on modern poetry, Logan begins by referring to Addonizio as "a hot babe who can bang out a sonnet on demand." This comment is not meant to be flattering, as the remainder of the review makes clear. Logan claims that Addonizio's poetry is "part of the latest contemporary manner—ha! ha! poetry can be just as dumb as television, too!" Logan continues his review with the comment that "too many of Addonizio's poems are made in Betty Crocker style, all helpful hints and ingredients whipped in a jiffy for a dish tasteless as a stuffed pillow." Logan concludes by suggesting that the problem with modern poetry is that too often the poet does not have anything to say. None of these reviews mention "Knowledge" specifically, instead focusing on the collection of poems as a whole.