Brain science is one of the more fascinating areas of current scientific research, and This is Your Brain on Music is an interesting window into current work. I was interested to read about the role of personal taste--if you love the music you are hearing, more of your brain becomes active.
I think that if one is purporting to study "music," more cultures are necessary. How about testing a few Indonesians? Or have societies not exposed to the commercial product disappeared from the earth? I read today in The Economist that the music industry is in free fall with no bottom in sight, so perhaps this state of affairs is about to change.
I agree completely with his general attitude that it is departure from expectations that produce the most sublime expression. Did I not say so here (one of my favorite postings)? However, a fully quantized (completely rhythmically regularized) midi file--the state of most midi files you will find on line--is not completely unmusical. Some may even imagine midi files are inherently this way. Rhythmical variation doesn't explain as much as Levitin wishes it did.
The most emotionally expressive musicians in any genre are the ones that sell. According to Levitin, expertise in anything requires 10k hours of practice. I liked it that he points out that music schools don't cover emotional expression. It is vital for an aspiring performer to get through his 10k hours as quickly and meaningfully as possible. You can't just add expression on later. Try to find a teacher who wants expression because it is in the individual lessons that true music is made.
Levitin is trying to have fun and doesn't try to be a textbook. He gives you the idea of it but not the true understanding. If you're not wanting to work too hard, this may be the book for you. I am not the target audience.
Toward the end he talks about how many times rock stars get laid, another of his 10k figures. I don't need to know this.