on the one hand, you have to give it credit for defining punk rock. i know this isn't done very often. zeppelin are usually cited as the antithesis of punk rock, and their own fans are happy enough to wear that designation. zeppelin and queen get skipped over in favour of garage rock and a collection of acts vaguely defined as "proto-punk". but, when you line this or stone cold crazy up against the stooges or the sonics, it's pretty obvious what was more defining.
on the other hand, it's the earliest example of nordic metal and, by extension, black metal. this song created a fucking monster of epic proportions. it makes you want to burn every copy of it in a fucking funeral pyre.
as for the song itself, it's a solid riff and one of the few examples where robert plant isn't overwhelmingly annoying.
http://www.youtube.com/watch?v=hC-T0rC6m7I