 Halliday's poetry is characterized by close observation of daily events, out-of-the-ordinary metaphors, unsentimental reminiscence, colloquial diction, references to popular culture, and uncommon humor.The poet David Graham has described Halliday as one of the "ablest practitioners" of the "ultra-talk poem," a term said to have been coined by Halliday himself to describe the work of a group of contemporary American poets, including David Kirby, Denise Duhamel, David Clewell, Albert Goldbarth, and Barbara Hamby, who frequently write in a wry, exuberant, garrulous, accessible style.Halliday has acknowledged the influences of New York School poets Frank O’Hara and Kenneth Koch on some of his poems.