It is the policy of the Longman Linguistics Library series to cover all aspects of linguistics, descriptive and historical, theoretical and methodological. Some of its books serve as introductions to key aspects of the subject, others are more specialized. In all cases the books are self-contained: they are intended to treat important areas in general linguistics and to be of value for a number of years.
as the title promises, it's an introduction, and it seems to be to be a pretty thorough one. the first half is about individual bilingualism, which is what was mainly of interest to me when selecting the book (since i'm planning on raising a bilingual). the second half is about bilingualism at a societal level, and that turns out to be pretty interesting too.
Excellent read. Very interesting and quite detailed but not dense. It is most definitely a bit dated at this point (USSR and West Germany were a thing still). I am curious to see how some of these concepts have evolved. Would recommend.