MACHINA is probably the album I most deeply got into. It's both engrossing and perplexing, and the lyrics can speak on so many levels. And the album art...wow, I just loved it. Everything seemed so beautifully complex and symbolic, like ancient religious art.
As for the
meaning, however, that was pretty much a lost cause. Billy Corgan probably had a lot of crafty fun confusing us with his mysterious symbols and practically indecipherable Glass story.
When I first listened to MACHINA, I still didn't know very much about Billy Corgan personally, and to me, the album sounded like he was in the midst of an existential crisis. Particularly with the song "Age of Innocence," which gave me the impression of an atheist coming to terms with a life lacking hope and faith. You can imagine the disappointment I felt when I later listened to the happy devotional twangs of Zwan. :P
Although MACHINA contains some of my absolute favorite songs ("Everlasting Gaze", "Stand Inside Your Love", "I of the Mourning"

, many of its songs were also pretty challenging, and it took me a while to warm up to them. Especially "Heavy Metal Machine" and "Glass and the Ghost Children." I used to not be able to stand those songs! (I still can't stand the alt. version of "Heavy Metal Machine" on MACHINA II) But given enough attention, MACHINA/the machines of God turns out to be a powerful and affecting album. It has an epic but tragic feel to it, and no one can achieve this better than the Smashing Pumpkins.