Never anything out of place. Every note correct. The whole thing is perfectly worked out. Ambrosian chant tends to be rough, not hewn as finely as the Gregorian. I don't like calling it primitive, because that puts a value judgment on it that I don't think is fair.
Ambrosian chant is less cultivated but maybe fresher.
Like most of the music usually performed at Present Music concerts, it has simple lines and it flows. And he should know. Back in the '50s, Weakland studied music at Julliard and Columbia, which was the sharp tip of the avant-garde in those days. He took courses in musique concrete , those early experiments in manipulating tapes into sonic sculpture and collage that are at the root of most everything in today's popular music, from Radiohead to rap. He tried his hand at composition, but found it not to his liking.