I've been reading a lot of Lester Bangs lately. Here's a segment from one of many articles about MMM by Bangs.
In 1975, Lester Bangs proposed six theories concerning Metal Machine Music. The list appeared in the September issue of Creem Magazine under the title “Monolith or Monotone?”
1. The new Lou Reed album is “some kind of ultimate antisocial act.”
2. It is the logical and inevitable culmination of aggressive tendencies that find their roots in early Velvet Underground albums and the Stooges’ Fun House.
3. It is the sound of anxiety. (“You know when you get so tense and anxiety-ridden that all the nerves at the back of your neck snarl up into one burning ball? Well, if that gland could make music, it would sound like this album.”)
4. Metal Machine Music is Reed’s circulatory system amplified.
5. The album is a corporate death wish in the form of a commercial suicide.
6. or “anybody who doesn’t jack off at least three times a day is a queer.”
http://machinemusic.org/2010/01/26/quadraphonic-lou-reed-and-the-metal-machine-music/
Then there's the classic article by Bangs titled "The Greatest Album Ever Made."
http://www.rocknroll.net/loureed/articles/mmmbangs.html
And from the collection of Bangs' writing: Psychotic Reactions and Carburetor Dung is this bit from Creem 1976, the article "How To Succeed in Torture Without Really Trying."
"What we have here is a one-hour two-record set of nothing, absolutely nothing but screaming feedback noise recorded at various frequencies, played back against various other noise layers, split down the middle into two totally separate channels of utterly inhuman shrieks and hisses, and sold to an audience that was, to put it as mildly as possible, unprepared for it. Because sentient humans simply find it impossible not to vacate any room where it is playing. With certain isolated exceptions: mutants, mental patients, shriek freaks, masochists, sadists, amphetamine addicts, hate buffs, drug-numbed weirdos too walled off by chemicals to feel anything, other people whose nervous systems are already so bent out of shape that it sounds perfectly acceptable, the last category possibly including the author of this article."
Also from an interview in Psychotic Reactions and Carburetor Dung, Lou himself states that he loves the album: "There are about seven thousand different melodies going on at one time or another, and each time around there’s more. Like harmonics increase, and melodies increase, in a different combination again. I don’t expect anybody with no musical background to get it. I took classical piano for fifteen fucking years."
BTW, I am one of the owners of MMM on BD-Audio.