The New Danger received generally mixed reviews from critics; it holds an aggregate score of 59 out of 100 at Metacritic.Blender called it "mushily sentimental, self-righteously indignant and constantly in your face", while AllMusic's Andy Kellman said it was "a sprawling, overambitious mess".New York magazine panned the album as "an unsatisfying muddle of protest music, black rock, and rap". In The New York Times, Kelefa Sanneh wrote that the record suffered from extended soul songs that meandered, dull rock songs, and some raps such as "The Rap Over" that were devoid of Mos Def's usual "warmth and wit".NME deemed some of the songs failed experiments but also highlighted "Boogie Man Song", "Modern Marvel", and "Champion Requiem" as more timeless material.Rolling Stone critic Tom Moon was more enthusiastic, hailing the album as an "earthy, impressively diverse" work that showcased Mos Def's abilities to "create deeply nuanced characterizations" and "broaden the hip-hop palette without sacrificing, or selling out, its core ideals". Writing for The Village Voice, Robert Christgau said while Mos Def's past records were driven by his "verbal flow", The New Danger was more interesting musically and defined by its sonic flow, which the critic described as "a shadowy, guitar-drenched tone poem of the streets". In his ballot for the annual Pazz & Jop critics poll, he named it the 19th best album of 2004.
The New Danger was released by Geffen Records on October 12, 2004, in the United States and October 18 in the United Kingdom. It debuted at number five on the Billboard 200 in its first week, and by March 2014, it had sold 513,000 copies in the US. In August 2017, the album was certified gold by the RIAA, indicating sales and their equivalents—streams and track downloads—of 500,000 units in the U.S.