^ This! Let's have a little music history, shall we?
Metal started with Black Sabbath. Black Sabbath inspired a lot of people into turning their music up, write darker songs, and having their drummer go mental on the drumset. This started the whole genre. After Sabbath, there was a lot of bands who followed through and kept the metal spirit alive, but the most famous ones are Deep Purple and, of course, Iron Maiden. Iron Maiden influenced a lot of other bands, and became what I would call "The new sound", be cause they took the doom'ish metal which Sabbath did, and the powerful metal-rock that Deep Purple did, and made it fast and even more powerful. This made a lot of people go into metal, and Iron Maiden is still considered one of the Gods of Metal. But the band that really made metal to what it is today, is Judas Priest. Judas Priest got inspired by Iron Maiden to move away from the glam-like rock they played, and they released their British Steel album in 1980 (as far as I remember)
That album changed the metal genre forever, and made it to what it is today. Later they released the Painkiller album, which is still considered the best metal album of all time amongst many metalheads.
Ehhh that's not entirely right, Judas Priest were before Iron Maiden also you seem to forget Thin Lizzy which was the main inspiration for Iron Maiden, which should be obvious when you hear this...
Basically that's how every Iron Maiden song sounds.