I found this article written by the ethnousicologist Horner worked with on Avatar. It should clear up some of the frustrations people have about this score, particularly those based on the comments Horner made about creating "sounds that no one has heard before."
"Creating the Music of the Na’vi in James Cameron’s Avatar: An Ethnomusicologist’s Role"
Interesting, thanks for sharing. I'll read it when I have an available moment.
I'm quite interested in the subject of ethnomusicology and film music, especially those that REALLY strive to purify the ethnicity of whatever idiom they're using. Mychael Danna is absolutely brilliant at this (rarely "washed out" by western Hollywoodisms).