I am a fan of Osvaldo Golijov and enjoyed very much his St Mark's Passion when I heard it in London. The difference between the passion and Oceana, which is supposed to be a preparation for the passion, or at least a stylistically related piece, may lie in the performance. In London the players and chorus were primitives from South America who sang in a raw style that very much attracted me. Oceana is performed here by the Atlanta Symphony Orchestra and Chorus, conducted by Robert Spano, and the severe, almost monotonous classical style of the chorus is distancing. Maybe you would prefer it that way, but I didn't. It doesn't put me all the way off. Like all of his music, it's fascinating.
The pieces Tenebrae I and II, played by the Kronos Quartet, and Three Songs with his muse, Dawn Upshaw, are gorgeous and quite somber.
Golijov achieves something that not many modern composers achieve: he makes you want to hear more.