The album was partially recorded with original guitarist Pete Willis, whose rhythm guitar tracks appear on all songs. Midway through the recording sessions, Willis was fired for excessive alcohol abuse and replaced by Phil Collen, who contributed guitar solos and other parts that had not yet been recorded by Willis. On the original LP release, Willis is visible in the background of the photograph of singer Joe Elliott, while Collen is given his own personal photo as the new full-time member of the group.
Pyromania has received mostly positive reviews, being commonly considered, along with its follow-up Hysteria, one of the band's finest efforts to date. Allmusic reviewer Steve Huey gave the album a rating of five stars and stated that it was "where the band's vision coalesced and gelled into something more." He also described the songs as "driven by catchy, shiny melodic hooks instead of heavy guitar riffs, although the latter do pop up once in a while", and later added that "transcendent hard rock perfection on Pyromania was surprisingly successful; their reach never exceeded their grasp, which makes the album an enduring (and massively influential) classic music.
With its melodic hooks and heavy MTV exposure, Pyromania became a massive success, and was the catalyst for the 1980s hair-metal movement. The album sold six million copies in the US in its original release (about 100,000 copies were sold per week for much of the year). It has since sold over ten million copies there and was certified diamond. Three songs, "Photograph", "Rock of Ages" and "Foolin'", became top 40 singles in the US. In 2004, the album ranked No. 384 on Rolling Stone's 500 Greatest Albums of All Time. In 2006, Q magazine placed the album at No. 35 in its list of "40 Best Albums of the '80s".