"Littlest Things" has met mixed reviews; Heather Phares from AllMusic complimented the song, saying the ballad softens Allen's rough image and celebrates "the mundane moments of a dying relationship", whereas "Blender" reporter Jon Dolan considers it a "forlorn single", where the singer writes about the terror of being in a relationship "with white-knuckled worry over a snip of florid piano from a ’70s soft-core porn flick".