Lauren Bacall in the script was originally much smaller, but during filming, her part was revised multiple times to extend it into the lead part that it became in the released film. Once released, "To Have and Have Not" catapulted Bacall into instant stardom, and her performance became the cornerstone of her star image, the impact of which extended into popular culture at large, even influencing fashion, as well as film-makers and other actors. Warner Bros. launched an extensive marketing campaign to promote the picture and to establish Bacall as a movie star. As part of the public relations push, Bacall made
What Love Is Made Of extremely positive about "What Love Is Made Of", describing it as "darker than anything" from "On a Mission", while calling it "slinky". The reviewer went on to commend the "irresistibly pouty" chorus. Pitchfork Media's Katherine St. Asaph commented that, in the song, the singer "sound[ed] completely enthralled, by either her lover or the music" and complimented her voice, noting that it seemed "ten times bigger than before". Jordan Sargent of "Spin" magazine called the track "exuberant" and highlighted Katy's vocal performance, which he deemed "typically fantastic", while the team from pop music website Popjustice gave "What Love Is Made Of"