This is Your Brain on Music by Daniel J. Levitin

 I haven't been keeping up with my non-fiction reading this year, but that's because this book took me the last two months to read.  Partly I wasn't giving enough time to it, but also this book is fairly technical and in-depth, so it was slow going.

Overall, I found the book interesting - I think a lot more research has to be done, but reading about some of the theories and studies was engaging.  My main complaint is that it sells itself as the answer to some very intriguing questions like why a song gets stuck in your head and plays over and over.  In the end, that was one part of one page and I wasn't really satisfied.