Written and produced by members Elly Jackson and Ben Langmaid, the track was a commercial disappointment despite acclaim from critics, peaking at number 153 on the UK Singles Chart upon limited release.

Digital Spy music editor Nick Levine wrote that "[l]ike most of the songs on their debut album, it's a winning combination of pop smarts, stifling romantic obsession and production that mixes the sounds of '82 with the sonic punch of '09.

"[5] Peter Paphides of The Times called the song "superb" and added, "Propelled along by a melody that shares some of its DNA with Prince's 'When Doves Cry', Jackson casts herself as the recipient of an overture from someone already in a relationship.

"[6] John Murphy, writing for musicOMH, described the song as "instantly addictive and catchy", while stating that "unlike a lot of electro acts out there, 'Quicksand' has real heart and emotion to it as well—certainly not a case of style over substance.

"[1] AllMusic's Heather Phares noted that the track "uses a relentlessly tight arrangement and Jackson's frosty soulfulness to give the song's obsession a shot of excitement.