To Be a Lover in early 1969. This version has since been sampled by Ludacris on his song "Growing Pains" from "Word of Mouf", by Jaheim on "Put That Woman First" from "Still Ghetto" and by Dilated Peoples on the song "Worst Comes to Worst". In 1977, the song was covered as a more uptempo reggae number by the Jamaican singer George Faith under the amended title of "To Be a Lover (Have Mercy)" for his Lee "Scratch" Perry-produced album also called "To Be a Lover". In 1986, the track was again reworked and became the second high-profile cover Billy Idol released as a
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"