Uum… well, tracer that’s a bit of an oversimplification wouldn’t you say?
As a big fan of minimal music perhaps I may enlighten a bit. First off I should say that Tracer’s explanation is pretty much dead-on as the reason why most people would bash his music. Stick on a Glass CD for most of the people you know, they are sure to respond with something to that effect (“It’s just the same thing over and over again. How boring!!”).
A few things about Glass:
He is a very visual composer. Many more people would agree that his score in any given film is very effective, than would agree that a CD of his is interesting.
He really has hardly grown at all as a composer in decades. So many of his recorded works are just the same thing with different instruments. Most of his music basically involves simple progressions of triadic harmonies arpeggiated with different instruments arpeggiating them in different patterns.
He was at a time (the 70’s) very ground breaking.
The Glass to own:
Einstein on the Beach - perhaps his most groundbreaking piece, a huge minimal opera from the 70’s. Different from most of his other stuff in that the harmony stays exactly the same (sometimes for longer than 20 minutes at a time) (i.e. no chord progression) and the same patterns repeat throughout. So what changes? The rhythm, or more often the meter (i.e. a pattern may play for 5 beats, and repeat this 2 or 4 times, then suddenly the same thing with the final beat removed so that it lasts only 4 beats. The meter keeps changing which really keeps you on your toes.)
Passages with Ravi Shankar. A truly beautiful recording which for the most part has very little to do with minimalism at all.
Koyaanisqatsi - I can take or leave Powa personally.
Aguas de Amazon - (or something like that). Same Glass as always but with this particular instrumentation (the group Uakti, a lot of wooden mallet instruments, and tropical-sounding flutes and stuff) it really is like a pleasant trip through the jungle on a river.
Steve Reich is infinitely more interesting than Glass. He began with tape stuff, as Tracer described, specifically having the same exact recording of a spoken phrase play on 2 tape decks that differ in speed by the tiniest fraction of a second. They would begin at the exact same time and seem to stay together for some time, but they would very gradually split and over the course of 10 minutes or so, many really neat musical things would happen. He brought this idea over to instruments and wrote some of the most interesting and influential music of the 20th century.
I’ll stop here, since you didn’t ask about Reich, but one more response to tracer’s post (and I promise to shut up for a bit). “Minimal” is not a term coined by composers to describe their own trend, but rather a term used by scholars in more or less retrospect. Thus there are as many kinds of “minimal” music as there are composers of it, and Reich and Glass are about 3 worlds apart. (though most minimal music usually involves some sort of repetition).
OK I’m done.