A live extended play (EP) of songs from the album was released in Germany in 2011 and plans for a concert tour were listed as "coming soon" on Duffy's website.

Aside from her partnership with Hammond, Duffy also forged collaborative efforts with other musicians who she felt reflected the sound change she was aiming for, including hip hop group The Roots.

The Daily Telegraph reports that often Duffy was a perfectionist regarding her songs, and that she often stayed in the studio with her mix engineer to ensure the composition sounded exactly as she wanted.

[15] Uncut noted that the album could be split into two-halves according to the "opposing moods" it contains–"saucy, sexed-up spin[s] around the dancefloor" and "soaring, superior ballads".

[17] In 2010, Billboard magazine was favourable in its preview of the album, introducing what it called the "funk-fueled" "My Boy", disco-esque "Lovestruck" and string-fuelled pop of "Keeping My Baby".

[1] It was praised for its use of keyboards and percussion, played by Hammond, said to "sound like piano's laughing", and "creating a preponderance of beats that dig themselves into your brain", respectively.

[26] Originally intended to be the second single released from the album, it was said to omit a tango style, and was both positively and negatively received by critics.

Said to debut Duffy's "inner diva",[15] the song, like "Mercy" (2008) is heavily influenced with Northern Soul,[13] aided by a rhythm section provided by The Roots.

[1] Duffy was able too secure their part in the song and others on the album through telephoning the president of Island Def Jam Records, LA Reid.

[13] Three downtempo ballads follow, called "the kind of songs you wouldn't want to listen to at all: the lyrics are boring at best and completely cliché at worst" by one reviewer.

[20] It also received praise concerning Duffy's voice, something that was a feature of many critics' reviews, with Sputnik Music noting, ""Hard for the Heart" [...] has the singer in an intensely emotional and surprisingly restrained moment.

Her beautiful timbre finally gets to shine without choking out the sophisticated and apotheotic production, giving pulse and strength to a strikingly poetic composition.

[44] The single was promoted extensively as part of a campaign of "major TV moments", taking in the UK, the United States as well as seven countries around Europe in 2010 and 2011.

[39] A second full single release was planned for the songs "Endlessly", "Keeping My Baby" and finally "My Boy" in 2011, and a music video was filmed for the latter in February 2011.

[47][non-primary source needed] The cover image itself is cropped from a larger version, in which Duffy is seen to be in a cafe holding a coffee cup.

[49] musicOMH was more negative, saying that it "looks like it ought to be adorning the latest Littlewoods catalogue", noting that it did not fit with Duffy's plan to "move her sound away from the middle of the road.

Melissa Maerz of Entertainment Weekly commended her choice to collaborate with Albert Hammond, stating that he was able to bring out "her inner pop star" on the record.

"[24] Similarly, a BBC Music reviewer praised the "rich, crisp production values" but ended by saying it is "too slight and uneven to impress unconditionally" and that Hammond's collaboration with Duffy "reaps only minor rewards.

"[56] Matthew Cole of Slant Magazine, giving the album one and a half stars out of five, said that "after 10 tracks of Endlessly, I was just begging her to stop", referencing her earlier hit "Mercy".

Okayplayer noted that the songs "capture a retro American sound reminiscent of sock hops and drive-ins so subtly, that the album could have been called Effortlessly.

"[57][59] Ann Powers of the Los Angeles Times notes that Duffy "tries several different ways to celebrate her unique talents without abandoning the vintage settings that won her such acclaim", calling the lead single a "reggae-tinged rocker" and complementing the return to Rockferry-like Northern Soul on tracks like "Too Hurt to Dance."

Matthew Cole of Slant Magazine said that "the bigger problem with Endlessly is that Duffy compensates for her lack of a star persona by overdrawing her syrupy rasp, already noted for its acquired tastiness, into a cartoonish oddity.

[65] Endlessly performed best in Denmark, where it reached a peak of number two on the Danish Albums Chart, spending thirteen weeks on the top forty.

[78] In 2018, Wales Online reported that Endlessly had sold 306,000 copies;[79] as of 2020, however, the BPI has not amended its certification from Gold to Platinum,[70] the threshold for which is 300,000 sales.

A&M Records' Orla Lee noted that the campaign would focus around "major TV moments", adding "[t]he thing with Duffy is it's about the voice [...] live, you really see that.

[8][82] In December, Duffy returned to perform at Capital FM's Jingle Bell Ball, where she sang two songs from the album and "All I Want for Christmas Is You" (1994).

[90] Outside of the UK and the United States, Duffy's record label revealed plans for her to visit Germany, France, the Netherlands, Italy, Sweden, Denmark and Spain before the end of 2010.

The first of these took place at the Café de Paris in London,[8] where fans of Duffy's could enter a competition to win tickets to the show, and members of the press were invited.

[95] The first of two live shows in the United States was at The Roxy Theatre in Hollywood, where Mercury Records invited fans to enter a competition to win tickets for the event.

Richard & Son Theater for iHeartRadio,[21] and included a cover of "Band of Gold" (1970), alongside the songs "Well, Well, Well", "Keeping My Baby", "Don't Forsake Me", "Endlessly", "My Boy" and "Mercy.