Powerful, beautiful...incredible. This is one of those albums I can only listen to once in a while simply because it's just so emotionally exhausting. I recommend listening to it lying on the floor in a quite room.
The music of the Bulgarian State Television Female Vocal Choir has been used in dozens of movies, movie trailers, and commercials; including the classic Japanese anime film Ghost in the Shell. They have also been samples and remixed by producers and DJs, especially in trance music.
This group was discovered by Swiss anthropologist/music producer Marcel Cellier during one of his excursion through Eastern Europe in the 70s. This is the same guy who discovered the Romanian pan flutist Zamfir. If that name doesn't ring a bell, you might recall his song "Lonely Shephard" that was used in Quentin Tarantino's film Kill Bill for that beautiful fight scene in the snow.
My favorite track has got to be number 3, "Kalimankou Denkou." That lead soprano gives me the chills!