I approached this book with some misgivings, expecting something like the Mammoth Hunters, which although worthy fiction never really convinced me of life in the Mesolithic. I was surprised to find nothing of the sort; this is a work of depth and texture, drawing on the author's knowledge of anthropology and tribes still living near-mesolithic lifestyles in the modern age.
It is unsentimental but the characters are real and identifiable. There is the suggestion that innovation is in the air, but the characters do not right all of the wrongs of the Mesolithic and set out on the road to the Neolithic. They seem to miss opportunities rather than grasp them - the wolf/dog crossover being the obvious example.
The Spirit World is the best part of this, allowing the author to explore the world inhabited by animals of the setting as well as the shamanistic practices and beliefs. The fact that the spirits who are bound to the tribe are as fallible in death as they were in life is also an interesting feature - after all, just because you ask the spirits for help, it does not mean that your situation will actually improve.
Finally the idea of kinship along the female line is presented here in a very unique way. It is not a perfect system, as they have the idea of incest as a strong taboo within the kinship group which is not reflected in exactly the same relationship if mirrored on the father's side.
This is a book I have re-read several times and it always rewards a return visit.