Miller does here what anthropology/ethnography is about, as far as many of its practitioners are concerned – he explores the ordinary and the everyday, in this case shopping as in basic provisioning. If it were an old style ethnography of some distant society, we'd talk about it as food gathering techniques, but in this case it is an ethnography of an area of North London.
He does two useful and important things – he explores the importance of the 'treat' – the thing we buy in most/every shopping outing that is special and for someone (maybe us) that by definition makes everything else ordinary – and 'thrift', a practice and discourse where spending money become saving (I got three for the price of two/saved money by buying something I didn't need because it was cheap and so forth). Secondly, and much more importantly, he explores everyday provisioning not as duped consumers being taken in by promotions and advertising but shopping as a kind of ritual practice that becomes sacrifice – so where a thing or activity become a way of sacralising something else – and in this case it is about making sacred the household/family within.
It is a challenging and in places difficult argument, but it is in the end very rewarding even if I don't buy into all of it. A valuable and important scholarly contribution to consumption studies, to anthropologies of the western world, and studies of gender.