The album was produced by Ronan McHugh and Def Leppard. It won a 2016 Classic Rock Roll of Honours Award for Album of the Year.
In August 2015, singer Joe Elliott stated that the album would consist of 14 tracks with a running time of around 55 minutes. Regarding the sound of the album, he explained "It's just called Def Leppard because that's what it sounds like. It doesn't sound like any one specific era of Def Leppard. It's got everything. Every single aspect of anything we've ever wanted to put out — acoustic, heavy, soft, slow, fast — it's there. That's why we call it Def Leppard because, just like Queen were, we're capable of coming up with vastly different kinds of songs."
Guitarist Phil Collen referred to the album as "probably the most diverse thing we've done" as well as "the best thing we've done since Hysteria" as it contains "the loudest rock guitars we've ever had on some tracks." However, he stopped short of calling it an "experimental" album, instead saying that it's "more liberating and expressive".
Vocalist Joe Elliott has described lead single and opening track, "Let's Go", as "a call to arms and a classic Def Leppard song. It's that three-minute pop-rock stuff with big chunky guitars and a big chorus. And it has that swaggering, mid-tempo rhythm, like "Pour Some Sugar on Me", and "Rock of Ages"." He described that the band wanted a familiar sounding song to introduce the album, being released several years after their previous album.
Joe Elliott, observed Classic Rock, "is the first to admit that Leppard aren't Bob Dylan. Sometimes they're barely even Bob the Builder. But then that's the beauty of it – if ever a band were cliché-proof, it's Def Leppard. If nothing else, you have to admire their sheer brass balls. With its crackling guitar and nuclear-detonation bottom end, 'Let's Go' doesn't so much revisit 'Pour Some Sugar On Me' as move into its spare room, steal its cornflakes and start sleeping with its wife. But even that pales into insignificance next to the finger-poppin' white-boy funk of 'Are You Man Enough?', which rips off Queen's 'Another One Bites the Dust' so shamelessly that it should come with its own stick-on handlebar moustaches… But for the most part, Def Leppard is the sound of a band who have rediscovered their sense of purpose."