Unusually, in these days of hype, it's everything the publisher says. It's beautfully written, hugely informative, a book to change the way you think both about sound, its place in biological evolution, and the workings and nature of the mammalian mind. Yes, you have to read each chapter three times, preferably marking key passages or especially memorable sentences (and there are a great many), and in that sense it's 'hard going'. But I can't recall ever having read a better fusion of hard science and stylistic grace. His big insight is that 'The mind sings', and he backs that mystical-sounding proposition up with detailed accounts of acoustic experiments that root the idea in objective data. It seems too to shed light on the processes involved in Mindfulness meditation, though he makes no mention of or claims about that.
I chanced upon a copy in the local library, but have now ordered my own. It's an excellent present for the right person too.