This album, to me, is their master of puppets or number of the beast. Seminal in so many ways.
I've been using bssm to teach with for many years- there are so many lessons in working with drummers, and using simple (as well as not so simple onesπ) counter melodies to emphasise elements.
I've always found the bass track relatively easy to hear in context. The tone as someone else mentioned, was a little of a surprise - it put me in mind of the isolated queen songs where John deacon's bass tone is filthy, but sounds really clean in the mix.
It's always an inspiring album for me and IMO their best and most mature work,despite the constant willy jokes in the lyric!