I read De Musica
for a medieval music class. My first impression? Augustine sure knew how to bore his readers. While Confessions
and many of his other works are (at least somewhat) theologically sound, De Musica
rambles on about the numerical importance of rhythm in music. Augustine constructs an elobrate yet faulty argument about the power of God manifested through the number of syllables in certain rhythmic patterns. It's all quite reminiscent of early Greek music criticism; Augustine isn't treading any new ground here, and he's certainly not rehashing it in an interesting fashion.
If you must read it, concentrate on Books I and VI. Book I provides an interesting definition of music (basically, he calls it "the art of skillfully making good sounds") that Augustine uses to set the tone for the rest of De Musica
. Book VI abandons most of the pointless metrical rhetoric and ambitiously attempts to frame music as some sort of transcendental, spiritual language. I wasn't convinced by his arguments, but it gave some insight into Augustine's opinions on art, truth and beauty.