An early example of how Jimmy Page wasn't afraid to shift gears and display some textural range in Zeppelin's songs. The legions of imitators who tried in vain to match Zeppelin's raw percussive power found out they had no chance matching the other end. Page and Jones were two of the most seasoned studio pros around and singers who tried to match the gravitas in Robert Plant's vocals often ended up sounding silly.
Page would get even more adventurous with the next release, Led Zeppelin III, one my favorite Zep releases along with Houses of the Holy.
Jimmy's solo sounds eerily reminiscent to one of those who idolized him most,, the great Tommy Bolin.