Yes, the music is very disturbing and depressive. But that was the goal of this soundtrack. To listen to it can be a torture or an enjoyment, because it is very diverse. But even the "muzak" clips sound depressing.
There is a feeling of loneliness, fear, helplessness and sadness, I never had when listen to music. Only Nitzsches "The Seventh Sign" can barely reach this level. But this soundtrack is much more intelligent. You really can hear the omnipotence of the dictatorship. Only in the last few minutes, when Schifrin incooperates the "Matthew Passion" from J.S.Bach very clever, there is a feeling of hope and liberty.
The metallic sounds are very interesting, and the use of silence. In some pieces, Schifrin uses silence as an instrument, like John Cage.
The soundtrack lives from the movie, but it also can stand alone.
If you hear it without seeing the movie its impressing.
If you have seen the movie, its a masterwork.
His best work, together with his Excorcist suite.