Well it took a bit of time to get round to the book, boycotting Amazon for one, reading the other two in the trilogy but itself finished in fairly quick time.
It is an excellent read, lots to think back, the winding of the two strands Colin and the stone age ancestor. Garner's writing is so staccato, short sentences and you realise you are reading something between prose and poetry.
Motifs are easily understood, the shaman, rock art, Meg/witch/goddess and the rather unglamorous figure of Colin.
I think there must be a problem with fictional children growing up, Rowling's Harry Potter and Lewis's Narnian children come to mind. Tolkien started his great epic fairytale with adults and escaped the predicament .....
I don't like either of the two main protagonists, Meg and Colin, one is a wimp and the other loudmouthed but the writing draws you on, especially the celtic like chant of the stone-age ancestor when he names the animals as he moves through the landscape "the bell of the deer" always invokes an image....
Ursula Le Guin in the Guardian ........
http://www.guardian.co.uk/books/2012/aug/29/boneland-alan-garner-review