2001 exhibits an expansion on Dre's debut G-funk sound and contains gangsta rap themes such as violence, crime, promiscuity, sex, drug use, and street gangs.

It produced three singles that attained chart success and has been certified 6× Platinum by the Recording Industry Association of America (RIAA); as of August 2015 the album has sold 7,800,000 copies in the United States.

When Aftermath heard that Priority and Death Row planned to use the same name for their album, Dre sought legal action.

Shortly after, Interscope began the main promotional campaign displaying a new release date, "October 26th 1999", and a new logo that drops the subtitle No Seeds.

At this point, Priority decided not to honor the original agreement and threatened to sue Dr. Dre if the Chronic trademark were to be used in any capacity.

In an interview with The New York Times, Dr. Dre spoke about his motivation to record the album and how he felt that he had to prove himself to fans and media again after doubts arose over his production and rapping ability.

He'll program a beat, then ask the musicians to play along; when Dre hears something he likes, he isolates the player and tells him how to refine the sound.

AllMusic writer Stephen Thomas Erlewine noted that Dr. Dre had expanded on the G-funk beats on his previous album, The Chronic, and stated, "He's pushed himself hard, finding new variations in the formula by adding ominous strings, soulful vocals, and reggae, resulting in fairly interesting recontextualizations" and went on to say, "Sonically, this is first-rate, straight-up gangsta.

"[12] Entertainment Weekly's Tom Sinclair depicted the album as "Chilly keyboard motifs gliding across gut-punching bass lines, strings and synths swooping in and out of the mix, naggingly familiar guitar licks providing visceral punctuation".

[16] PopMatters praised the production, stating that "the hip-hop rhythms are catchy, sometimes in your face, sometimes subtle, but always a fine backdrop for the power of Dre's voice.

[18] The album marked the beginning of Dr. Dre's collaboration with keyboardist Scott Storch, who had previously worked with The Roots and is credited either as a co-writer or performer on several of 2001's tracks, including the hit single "Still D.R.E.".

They include many themes associated with gangsta rap, such as violence, promiscuity, street gangs, drive-by shootings, crime, and drug usage.

Stephen Thomas Erlewine said that the only subject matter on the album was "violence, drugs, pussy, bitches, dope, guns, and gangsters" and that these themes have become repetitive and unchanged in the last ten years.

[8][13] NME mentioned that the album was full of "pig-headed, punk-dicked, 'bitch'-dissing along with requisite dollops of ho-slapping violence, marijuana-addled bravado and penis-sucking wish fulfillment.

Many critics cited the last track, "The Message"; a song dedicated to Dr. Dre's deceased brother, as what the album could have been without the excessively explicit lyrics,[16][18] with Massey calling it "downright beautiful" and "a classic of modern rap".

[21] The song was nominated at the 2000 Grammy Awards for Best Rap Performance by a Duo or Group, but lost to The Roots and Erykah Badu's "You Got Me".

[30] Stephen Thomas Erlewine of AllMusic stated, "2001 isn't as consistent or striking as Slim Shady, but the music is always brimming with character.

"[12] Entertainment Weekly's Tom Sinclair praised the production, calling it "uncharacteristically sparse sound" from Dr. Dre and that it was as "addictive as it was back when over 3 million record buyers got hooked on The Chronic and Snoop Dogg's Dre-produced Doggystyle" and went on to commend Dr. Dre, stating, "If any rap producer deserves the title "composer", it's he.

"[13] NME mentioned that Dr. Dre didn't expand the genre, but it was "powerful enough in parts, but not clever enough to give Will Smith the fear".

[16] PopMatters writer Chris Massey declared that "Musically, 2001 is about as close to brilliant as anyone gangsta rap album might possibly get.

"[17] Christopher John Farley of Time stated that "The beats are fresh and involving, and Dre's collaborations with Eminem and Snoop Dogg have ferocity and wit.

"[31] Although he was ambivalent towards the album's subject matter and guest rappers, Greg Tate of Spin was pleasantly surprised by "the most memorable MC'ing on this album com[ing] from Dre himself, Eminem notwithstanding" and stated, "Whatever one's opinion of the sexual politics and gun lust of Dre's canon, his ongoing commitment to formal excellence and sonic innovation in this art form may one day earn him a place next to George Clinton, if not Stevie Wonder, Duke Ellington, or Miles Davis.

"[28] In a negative review, Robert Christgau from The Village Voice found Dr. Dre's lyrics distastefully misogynistic, writing "It's a New Millennium, but he's Still S.L.I.M.E.

[13] NME spoke of how the lyrics were too explicit, stating, "As the graphic grooves stretch out, littered with gunfire, bombings and 'copters over Compton, and the bitch-beating baton is handed from Knock-Turnal to Kurupt, 2001 reaches gangsta-rap parody-level with too many tracks coming off like porno-Wu outtakes.

"[34] During the hype of the nu metal era, the band Korn kept Dr. Dre from hitting number 1 in America's Billboard 200 with their album Issues, which sold 575,000 copies in its first week.