nope,i thought zep 2&4 were good albums but I dont think they deserve their ultra legendary status personally,much of this came about due to the manager (Peter Grant) being a very shrewd operator,while all the other bands were touring relentlessly and on TV every chance they got,he limited Zeps appearances on stage and they rarely appeared on TV or gave interviews.He then created an air of mystery around them by carefully leaking stories as and when it suited.This tactic made them stand out from the rest of the bands of the era - Deep Purple etc.
I re-watched "The Song Remains The Same" a few months ago and tbh I thought the performance was dreadful.But these things are very subjective,one mmans ceiling is another mans floor etc.

As for being unique,I think its debatable,the big leap in electric guitar music was when Clapton recorded the "Beano" album with Mayalls bluesbreakers that really took Blues based music in a whole new direction and set the tone for what followed,interestingly iirc Jimmy Page was a sound engineer or similar on that album so maybe that was the inspiration for taking the Blues to a different place,which was what he did with Zep,but personally I didnt really like where he went with it and I also think (controversial I know) that he has been quite over rated as a guitarist.
Anyone who is unsure I would recommend an open minded viewing of "The song remains the same"