It Was Written received generally positive reviews from critics. The Source called it an "audio anthology of ghetto stories told by one of hip-hop's most prolific writers." Vibe magazine's Krisex criticized the album's "consistently aggressive attempts at pop music", but also wrote that Nas "shines through". Despite calling the album "adequate" and commending Nas for his lyricism and flow, Krisex concluded that It was Written "isn't nearly as satisfying as his first one." NME wrote that "Nas' neat, considered lyrics treat the violence that surrounds him with a mixture of remorse, resignation and ebullience." Christopher John Farley of Time stated "The lyrics in It Was Written could be sharper, but the music, energetic and engaging on many tracks, helps drive his message home." Q magazine called Nas's performance "angry, lean and full of drive." Both the Chicago Tribune and Chicago Sun-Times were favorable of the album's sound and gave the album 3½ out of 4 stars. Los Angeles Times writer Cheo Coker called the album "poetic", writing that it "demonstrates a continuing lyrical maturity that makes his already potent beats and rhymes all the more compelling". Spin magazine preferred the "reach" of It Was Written to Nas's "more suavely rapped debut", praised the production, and described the songs' choruses as "grainy, pop-savvy".
The album's release followed the commercial success of other mafioso-themed rap albums with similar subject matter, including Raekwon's Only Built 4 Cuban Linx… (1995), Jay-Z's Reasonable Doubt (1996) and AZ's Doe or Die (1995). Music writers criticized its mainstream, R&B and pop-leaning sound, as well as the enlistment of a top production unit and popular guest artists. The album's lyrics and themes were also poorly received and heavily dismissed as an attempt by Nas to follow the popularity of gangsta and mafioso rap. Rolling Stone's Mark Coleman wrote negatively of Nas's themes and called it "the latest blatant example of trashy tough-guy talk", writing "Certainly he strikes a note of creepy realism in his stories of heavyweight dealing and literally cutthroat competition. 'The Set Up', 'Shootouts' and 'Affirmative Action' [...] are chilling in their how-many-grams-to-a-kilo detail and utter amorality. On 'Watch Dem nikkas', Nas cites as inspirations both the boxing coach Cus D'Amato and the murderous drug lord Pablo Escobar. What is this guy thinking?". Jon Pareles of The New York Times commented that he "continually shifts perspective" and called it "late-stage gangsta rap, starting to buckle under its own contradictions." The Village Voice's Robert Christgau gave the album a "neither" ((neither)) rating, indicating "may impress once or twice with consistent craft or an arresting track or two. Then it won't."
The album was ranked number 41 in NME's critics' poll of 1996, and Jim Farber of the New York Daily News named it the sixth best album of 1996. German-based magazine Spex ranked it number four on its "End of Year" list, while the UK-based magazine The Face named it the twenty-fourth best album of 1996. "If I Ruled the World (Imagine That)" was ranked number 29 on NME's Singles of the Year list, and number 20 on The Village Voice's Pazz & Jop critics' poll. It was nominated for a Grammy Award for Best Rap Solo Performance in 1997.