Kashmir is the highlight of the album and probably is the best song of the album however I kinda think the song is a bit redundant due to songs that taken influence from it and made it better.
Kashmir essentially has 3 sections in the song.
The opening riff (you know da-da-da pause)
The horn section riff
The mellotron section - you know the "All I see turns to brown As the sun burns the ground"
I just think those three sections have been incorporated by far better songs that stole from Kashmir
The opening riff - Squackett - A Life within a day
The horn section riff
Paul McCartney - Nod your head (0:34) (although the riff is played by the strings in McCartney)
The Mellotron section
REM - Feeling Gravity's Pull - ending of song
Why do I rate all those songs better than Kashmir
Because all those songs don't stretch out their limited (although admittingly great) ideas up to 8:40 seconds like Kashmir. They are just represented either as a verse (with Hackett), or instrumental break (McCartney) or an ending of a song (REM). Instead of just repeating these section ad nauseum for 8 minutes non stop
Feelings of listening to Kashmir is essentially initially - "hey this is cool" that quickly turns to "hey this is boring" as the song is inefficiently stretched out instead of the more compact songwriting of the examples I listened to.
Now I know some people may say that since those songs copied Led Zeppelin it can't be better.
Well if you believe that then you have to believe that Led Zeppelin are a bad band because Led Zeppelin made an entire career of copying other people melodies, riff etc and transforming the material in a more interesting arrangement that transcend the original material. If anything Led Zeppelin biggest weakness is that they should have plagiarise more often not less (plagiarism shows they know their limitations and hence are "adequate". Physical graffiti would have been a better album with more plagiarism as the album doesn't have good songwriting even if the album sounds good from a timbre/production point of view). IF Led zeppelin can transcend blues standard, other songwriters can similar do the same thing with Led Zeppelin riffs.