Davies included the song on the original 12-track edition of The Kinks Are the Village Green Preservation Society (1968), but removed it from the LP in a last-minute decision to expand the album's track listing.
[5] Miller writes Davies employs his "one hard line" technique in the song, with its final lyric about keeping the devil at bay containing genuine fear.
Compiler Andrew Sandoval compares the trills to Zal Yanovsky's guitar work on the Lovin' Spoonful's 1967 song "You're a Big Boy Now".
[13] In his September 1968 review of the album for New Musical Express, Keith Altham describes the song as different from the band's typical sound, its simple format being "[a]s obvious as a cup of tea.
"[2] Miller questions why "Wonderboy" was released as a single in April 1968 in place of the "sublime" "Mr. Songbird", since the latter features both a "blithe melody and toe-tapping arrangement".
[17] Geoffrey Himes of Paste magazine likens the lyrics to a Disney film while suggesting its melody is comparable to the best written by musician Paul McCartney.