Having never seen nor heard of GI3P when I found the Soundtrack LP, I assumed that it was just that: a soundtrack, to a film probably. I liked the LP immediately, reminding me of Vileness Fats, and played it to death.
A couple of years later, I was rummaging through some cheap CDs, and discovered and bought GI3P — interested to hear the other 15 minutes. Imagine my surprise when the introduction had singing in it, and that Resident talked through most of the rest. I wasn't impressed. In fact, I can't actually listen to the CD all the way through, unless I've had a good night's sleep.
So my advice, to anyone thinking of buying the soundtrack, is: if you prefer Intermission and Vileness Fats to King and Eye or 13th Anniversary Show, get it.