The album has often been noted by critics for producer Leon Ware's cinematic, downtempo sound, the erotic themes in his and Gaye's songwriting, and the singer's prominent use of the synthesizer.

The album's cover artwork adapts neo-mannerist artist Ernie Barnes's famous painting The Sugar Shack (1971).

While it marked a change in musical direction for Gaye, departing from his trademark Motown and doo-wop-influenced sound for funky, light-disco soul, the album maintained and expanded on his previous work's sexual themes.

In his book Mercy, Mercy Me: The Art, Loves, and Demons of Marvin Gaye, the author and music writer Michael Eric Dyson elaborated on the relationship between I Want You and Gaye's affair with Hunter: "I Want You is unmistakably a work of romantic and erotic tribute to the woman he deeply loved and would shortly marry, Janis Hunter.

Gaye's obsession with the woman in her late teens is nearly palpable in the sensual textures that are the album's aural and lyrical signature.

Gaye's vocalizing style was in classic doo-wop tradition accompanied by the low tempo of string arrangements and other instrumentation was provided by the Funk Brothers.

[2] EMI Artists and Repertoire executive Gary Harris, who later assisted neo soul singer D'Angelo in recording his debut album Brown Sugar (1995), later commented on Gaye's significant artistry on I Want You and its opening title track.

[6] In an interview with writer Michael Eric Dyson, Harris comments on another popular track from the album "Soon I'll Be Loving You Again": With the opening, with the congas and the strings; it's like the sun is rising.

[1] During the time of recording, the instrument had entered its modern period of use and had been included in the music of such popular acts as Stevie Wonder and Led Zeppelin.

[7] In 1976, Barnes redesigned the painting for use by television producer Norman Lear for the opening credits of Good Times,[8] his hit CBS sitcom that ran from 1974 to 1979.

Any Mannerist painter would be proud of the succession of figures in the main, central group of dancers, but the whole is infused with the innocent exuberance of Breughel and his fellow Flemings.

[22] While not as successful sales-wise as Gaye's previous landmark albums What's Going On and Let's Get It On, I Want You sold in excess of 1 million copies in the United States with help mostly coming from its first single "I Want You".

[2] "After the Dance" was hailed as one of Gaye's signature songs during the late 1970s and was later described by Gaye-biographer David Ritz as "emblematic for the final chapter of his career.

[23] Rolling Stone's Vince Aletti criticized Leon Ware's production for being too low-key, and perceived that Gaye lacks the certain passion in his lyricism and singing from his previous records.

I Want You continues in the same vein but with only the faintest traces of the robust passion that shot through and sustained the earlier album ... one expects something with a little more substance and spirit.

"[24] Cliff White of NME called the album "almost a voyeur's delight", and was not favorable of Gaye's sensual themes, stating "Although getting down, getting mellow, and getting it on are paramount considerations in the privacy of my own home, I don't particularly want to be party to someone else's night life.

[26] Its standing has also improved among critics following an expanded edition release of the album on July 29, 2003, which featured extensive liner notes and photography by Ryan Null.

They are adult albums about intimacy, sensuality, and commitment, and decades later they still reverberate with class, sincerity, grace, intense focus, and astonishingly good taste.

"[28] Much like Let's Get It On, slow jam music, as well as modern soul and the quiet storm genre, are now viewed by critics to have been engendered by I Want You and by Gaye.

[2] Critical recognition of Ware's album later improved, being cited by AllMusic as "the perfect mix of soul, light funk, jazz, and what was about to become the rhythmic foundation for disco.