[5][7] It has a measured pace and features slight vocals and whispered cadences by Croft,[4] background baritone bass,[6] subtle drum thuds,[8] and coiling guitar lines.

"[13] Croft's transparent lyrics express lovesick emotion,[4][14] adoration,[15] and private knowledge acquired from intimacy:[16] "You move through the room / Like breathing was easy / If someone believed me / They would be as in love with you as I am".

"[3] Puja Patel of Spin characterizes its subject matter as "loverlorn" and observes a balance "between honest[y], gut-wrenching desire and stalker-like idolization".

[20] Pitchfork Media's Larry Fitzmaurice noted the song's "percussive touch" as an indication that "the xx are changing ... slowly and subtly, two characteristics that's always been part of their central appeal.

"[10] Siân Rowe of NME called it "a heart-meltingly perfect follow-on from their debut",[21] and the magazine's Priya Elan dubbed it "the boldest Valentine the band have ever recorded.

"[11] Allmusic's Heather Phares called the song a "lovely album opener" and wrote that the band's "elegantly serpentine guitars — which recalled the Cure and Durutti Column on xx ... are now entirely their own".

[12] Brendan Frank of Beats Per Minute commended Croft for "delivering a simple love note to an anonymous recipient," adding that "she does a magnificent job of carrying the piece on her own.

"[22] Stephen Thompson of NPR called "Angels" a "gentle love song made all the more disarming for its simplicity," writing that it "ratchets up the tension using the fewest possible ingredients.