Even before his temporary departure from the Beatles in January 1969 (documented in the song "Wah-Wah"),[3] their Apple Records label was an "emancipating force" for Harrison from the creative restrictions imposed on him within the band, according to his musical biographer, Simon Leng.

[4] In his article on All Things Must Pass for Mojo magazine, John Harris has written of Harrison's journey as a solo artist beginning in November 1968 – when he spent time in Woodstock with Bob Dylan and the Band – and incorporating a series of other collaborations through the following eighteen months, including various Apple projects and a support role on Delaney & Bonnie and Friends' brief European tour.

[5] One of these projects, carried out intermittently from April to July 1969,[6] was his production of That's the Way God Planned It, an album by Billy Preston, whom Harrison had met during the Beatles' Hamburg years and had recently been recruited to guest on the band's troubled Get Back sessions.

[10][9] Rather than attempt it with the Beatles during the band's concurrent Abbey Road sessions, Harrison stockpiled "What Is Life" with his many other unused songs from the period, including "All Things Must Pass", "Let It Down", "I'd Have You Anytime" and "Run of the Mill".

[21][nb 1] Joshua Greene, another religious academic, identifies the song as part of its parent album's "intimately detailed account of a spiritual journey": where "Awaiting on You All" shows Harrison "convinced of his union with God", "What Is Life" reveals him to be "uncertain that he deserved such divine favor".

[25] With Phil Spector as co-producer and all the Friends team on hand, the song was among the first tracks taped for Harrison's debut post-Beatles solo album;[26] recording took place at Abbey Road Studios in London, during late May or early June.

[9][32] During the verses, Gordon moves to a square, Motown-style beat – or "rock-steady Northern soul backbeat" in Leng's words[25] – before returning to the "galloping rhythm" of the more open, "knockout" choruses.

[17] On "What Is Life", Spector provided what music critic David Fricke terms "echo-drenched theater", in the form of reverb-heavy brass, soaring strings (arranged by John Barham) and "a choir of multitracked Harrisons".

[36] In MacFarlane's description, the strings provide a complementary countermelody to the guitar riff, while the horns' combination of "uptown soul and mariachi" heightens and expands the track's musical colour.

[46][47] Billboard magazine's reviewer described "What Is Life" and "Apple Scruffs" as "intriguing rhythm follows-ups" to the first single, which were "sure to repeat that success" and "should prove big juke box items".

[49] While describing the initial impact of All Things Must Pass, author Robert Rodriguez includes the song as an illustration of how the depth of Harrison's talents had been "hidden in plain sight" behind John Lennon and Paul McCartney during the Beatles' career.

[50] The album introduced Harrison as an overtly spiritual songwriter who sought to connect with his audience on a "higher level" compared with the populist approach of McCartney or the confrontationalism adopted by Lennon.

Rodriguez concludes: "That the Quiet Beatle was capable of such range – from the joyful 'What Is Life' to the meditative 'Isn't It a Pity' to the steamrolling 'Art of Dying' to the playful 'I Dig Love' – was truly revelatory.

[52] This picture was taken by photographer Barry Feinstein, whose Camouflage Productions partner, Tom Wilkes, originally used it as part of an elaborate poster intended as an insert in the album package.

[1] In their Solo Beatles Compendium, authors Chip Madinger and Mark Easter refer to it as an "intensely catchy track" and view its pairing with "My Sweet Lord" in the UK as perhaps the strongest of all of Harrison's singles.

[70] Reviewing the 2001 reissue of All Things Must Pass, for Rolling Stone, James Hunter wrote of how the album's music "exults in breezy rhythms", among which "the colorful revolutions of 'What Is Life' ... [move] like a Ferris wheel".

[16] Writing in the book 1,000 Recordings to Hear Before You Die, author Tom Moon refers to "the upbeat single 'What Is Life'" as an example of how Harrison "grabs what he needs from his old band – that insinuating hook sense – and uses it to frame an utterly comfortable metaphysical discourse".

[25] Ian Inglis is less enthusiastic, acknowledging that Barham's orchestration and the other musicians give the track "undoubted excitement and energy", but lamenting that the song offers "little overall coherence between words and music".

[18] In Thomas MacFarlane's view, "What Is Life" is a "remarkable pop song" that "takes the tone and attitude of Phil Spector's Wall of Sound and channels it through the prism of the late-period Beatles".

[31] In 2009, Matt Melis of Consequence of Sound listed it sixth among his "Top Ten Songs by Ex-Beatles", writing: "it's arguable that Harrison's All Things Must Pass is the best solo album put out by a Beatle.

[86] The song has also appeared in several popular feature films: Martin Scorsese's Goodfellas (1990),[87] during the "May 11, 1980" sequence; Tom Shadyac's Patch Adams (1998); Sam Mendes' Away We Go (2009); Judd Apatow's This Is 40 (2012),[84] for which it was also used in advance promotion;[88] and Instant Family (2018), directed by Sean Anders.

[98] Speaking to Billboard editor-in-chief Timothy White in December 2000, Harrison explained the reason for the lack of a guide vocal on this version: "I'm playing the fuzz guitar part that goes all through the song.

[116][117] Simon Leng writes of a Fort Worth performance of "What Is Life" that was "greeted with a reception that matched anything the New York audience at the [August 1971] Bangla Desh concerts expressed".

[122][nb 7] The song's chart run coincided with Newton-John touring the UK with French balladeer Sacha Distel before beginning a season of solo concerts at London's Prince of Wales Theatre.

[17][131] In 1971, British easy listening pianist Ronnie Aldrich covered it (as well as "My Sweet Lord") on his album Love Story, giving the track what AllMusic reviewer Al Campbell views as a regrettable "Muzak arrangement".

[132] That same year, the Ventures included an instrumental version on their New Testament album,[133] recorded when the band had progressed from their surf rock roots to embrace fuzz-tone and other heavier guitar sounds.