St. Anger received polarized reviews from critics; the album holds a score of 65 out of 100, based on 20 reviews, on review-aggregating website Metacritic. Adrien Begrand of PopMatters noted positive and negative aspects of the album, saying, "While it's an ungodly mess at times, what you hear on this album is a band playing with passion for the first time in years." Talking about the album, Greg Kot of Blender said, "It may be too late to rehabilitate Metallica's image, but once again, their music is all about bringing the carnage." Writing for NME, Ian Watson said that, "the songs are a stripped back, heroically brutal reflection of this fury. You get the sense that, as with their emotional selves, they've taken metal apart and started again from scratch. There's no space wasted here, no time for petty guitar solos or downtuned bass trickery, just a focused, relentless attack." Johnny Loftus of AllMusic praised the album and described it as a "punishing, unflinching document of internal struggle—taking listeners inside the bruised yet vital body of Metallica, but ultimately revealing the alternately torturous and defiant demons that wrestle inside Hetfield's brain. St. Anger is an immediate record." Barry Walter of Rolling Stone magazine also had a positive reaction to the direction taken on St. Anger, stating: "No wonder there's an authenticity to St. Angers fury that none of the band's rap-metal followers can touch." He also went further to note the lack of commercial influence and modern rock aspects of previous albums, continuing: "There's no radio-size, four-minute rock here, no pop-friendly choruses, no ballads, no solos, no wayward experimentation."
