"When rating this album, it is not fair to compare it to their other albums. Undertow was less hard and more melodic, Aenima maintained some of the rock elements but was more experimental and psychedelic, and Lateralus was marked by the evolution of Tool from hard rock to progressive. Tool was just starting out as a band in 1992, fresh out of the pretentious art scene in Los Angeles. Opiate showed that they were a hardcore band, that had some real statements to make. All fans of Tool should check out Opiate, because it's important to know what Tool evolved from. For fans of metal, you may want to give it a listen, but it's not a particularly special work of metal or anything, just kick-ass."

- ocelot-05, sputnikmusic.com