I had some ideas of what this would sound like before I heard it, but when I heard it I realised I was completely wrong! I thought that it would be typical Philip Glass with some sitar and Indian scales and sounds. It is nothing of the sort.
Each track is not so much a collaboration as a joining of distinct parts. You can hear which parts are Glass and which parts are Shankar, but the glue that holds them together is the compositional genius of the two men. It does not just encompass India either, as there are Middle-Eastern motifs and scales used here, and some very Western orchestral parts.
It is very light on the sitar, and Ravi Shankar probably has more input vocally than with his sitar playing. This is orchestral music without using a conventional orchestra from the West. It is Indian music without being limited to the traditional Indian instruments and arrangements. It is World Music at its best!