Janet Holmes is Professor of Linguistics at the University of Victoria in Wellington (New Zealand). Sociolinguistics is the study of the relationships between language and society.
The book is structured like a school manual for students on the topic, but targeted to laid readers. Such a formal approach could have been a good academic overview, be a great way to introduce the subject to beginners while missing nothing of the field's key notions. Well, as far as I am concerned, it fails!
Of course, concepts are defined, explained, and illustrated through exercices allowing thus to better assimilate the relevance of the arguments put forward. The thing is, these exercises are too many, and even if you fly over them all the fact they can't be separated from the rest of the text render such read quite boring. Plus, it's all very confused: problems specific to multilingual societies are coming right into the middle of a discussion on societal factors affecting speech; and from diglossia we suddenly jump to the issue of the death of certain languages before coming back again to the differences between pidgin and creole! Unfocused, it goes randomly in all directions without a logical structure, and so turns quickly annoying.
The only positive is that she introduces, rigorously, the works of some eminent researchers when it comes to the core of the topic -genderlect, bilingualism/multilingualism, language use in the medias… Good on that! But would you buy a book solely for its bibliography?