Critical reception The album received favorable reviews. At
Metacritic, which assigns a normalized rating out of 100 to reviews from mainstream critics, the album received an average score of 63, based on 10 reviews, which indicates "generally favorable reviews".
Stephen Thomas Erlewine from
AllMusic gave the album 4 out of 5 stars, writing, "Mraz pushes himself into new territory, creating music that's perilously close to sounding seductive." Kyle Anderson wrote for
Entertainment Weekly that "he tiptoes the line between hammock-strung wisdom and twee naïveté with such goofball charisma that otherwise forgettable love-each-other-doodles become sweetly breezy anthems." Matthew Horton from
Virgin Media wrote that "It's all light as air, of course, and corny as hell but Mraz isn't here to kick James any statues. If you're after unchallenging whimsy with the odd sparky arrangement he'll continue to do just fine." Caroline Sullivan from
The Guardian complimented "his words with a variety of genres that show him to be a cracking musician." She also wrote that "this is pure, undemanding pleasure: his voice has a natural affinity with elegant lounge-jazz and introspective folk-blues, as well as the delicately hewn soft rock that made his name." Sandy Cohen from
The Boston Globe wrote, "The songs about heartache don't detract from the optimistic vibe of this 12-song collection." Jon Caramanica from
The New York Times criticized the album, writing that the album is "filled with platitudes and, eventually, psychobabble, dippy even by Mr. Mraz's standards." Phil Mongredien from
The Observer gave the album only 1 star out of 5, writing that "the lyrics alternate between the ludicrous and the banal." Amy Dawson from
Metro UK wrote that "Mraz's earnest, melodic guitar pop exerts mainstream appeal, but this will all be a bit earnest teen drama soundtrack for some." Loh Chuan Junn from
MediaCorp's xinmsn opined that "every song on this album is listenable, but when put on loop, Mraz's relentlessly upbeat and happy romanticism grows increasing annoying for even the least cynical."
Commercial performance In the United Kingdom, the album debuted at number two on the
UK Albums Chart behind
Adeles
21 by a margin of 44 copies. It sold 17,021 copies and is Mraz' highest-charting album there. In the United States,
Love Is a Four Letter Word debuted at number two on the
Billboard 200, becoming his highest-charting album. It sold 102,000 copies in its first week, his best sales week to date. In Canada, the album debuted at number one on the
Canadian Albums Chart, selling 19,300 copies, making it Mraz' first number one debut in Canada. Up to April 24, 2014, the album has sold 547,755 copies in the United States. It has been certified Gold in Brazil. ==Singles and promotional singles==