If you're looking for the album that really kick-started the whole Heavy Metal thing, this is it. Whether it's to blame or praise for that is subjective.
After crashing out of the gates with The Hindenberg Album, Page / Plant / Jones / Bonham found themselves touring America for the first time - bringing the Hammer Of The Gods to the states. Their performances were already becoming legendary: stretching out selections from their first album and improvising musically and vocally on pretty much three-quarters of their setlist. They were definitely becoming the hottest thing in rock'n'roll.
As a result of their full schedules, Led Zeppelin II sounds fast and loud. It's one of the greatest road albums ever made. From the thunderous reworking of Willie Dixon's "You Need Love" that became their biggest "hit" (while "ABC" by the Jackson 5 kept "Whole Lotta Love" from reaching the top spot), to the subtle closing of their reworking of Sonny Boy Williamson II's "Bring It On Home", this is an album that makes long vehicular journeys more enjoyable than the destination.
Sure, I have a beef with the Page / Plant or Bonham / Jones / Page / Plant credits on the blues songs. It is a shameless and unforgivable discredit those who influenced them. In the end however, it does not take away from the power of the arrangements, and if it made one kid curious about Robert Johnson, Muddy Waters, Rice Miller, or Howlin' Wolf (all who are uncredited "contributors" to songs on the record), then I guess that's a good thing in and of itself.
But as for the true originals, they are incomparable slabs of the greatest hard rock ever recorded. These songs are so woven into the consciousness of rock'n'roll - just like "Johnny B. Goode" or "Whole Lotta Shakin' Goin' On", that it's hard to remember a time now when they did not exist. That is a testament to true talent.
Most amazingly, this album, close to 34 years old now, still sounds fresh, vibrant, urgent, and necessary. And it is.