Chambers and Trudgill between them account for at least 51% of non-urban dialectology at the present moment, so you know this is gonna be two guys that know their stuff. And they do, balancing advocacy, and a salutatory readiness not just to cite studies but to take us through them in all their fascinating parts, with an equally strong sense of its limits--the feebleness of the isogloss, the simultaneous reductiveness and over-refinement (!) of sociological class models when applied to language variation, the way spatial diffusion,much as we can represent it with an equation, is still basically a huge question mark as far as motivations are concerned. As luminaries of a niche discipline, they talk as much to their colleagues as to the students who will ostensibly be using this textbook, and it's fair criticism to say that this is gonna be steep going for a lot of the English students who are interested in this stuff (until, as C&T predict, dialectology gets wholly subsumed in variation theory and recognized as something you need a linguistics background to do with relevance. Nevertheless, it's ultimately usable as an undergrad textbook because it lays out its terms clearly (though in advanced language) and gives a thorough grounding in the canonical studies and disciplinary mythology, from Wenker and Gillieron in the 19th century to Kurath walking New England, the Milroys in disintegrating Belfast, Labov bugging moms in Saks, Wakelin's work on why Yorkshiremen say "motherloving gutterpunks" and "monkey's uncle" like that, Chambers himself and the search for "chesterfield", of all Canadianisms less lame only than "serviette" (which I actually heard a barista say the other day in Victoria! a young, attractive man!), the crazy sprachbund action in European languages, with uvular /r/ and affricated palatals (good ol'english "ch") splayed willy-nilly across linguistic boundaries, and,oh,plenty of more. But it's also a good text because it communicates the fun of this occasionally (for all its mighty and still-being-realized implications) less-than-momentous (see, again, "chesterfield") but endlessly amusing and whimsical corner of linguistic study. ( )

This book gives a very comprehensive and approachable introduction to the domain of research, which is fortunate, because there aren't a lot of books on the subject, especially ones that present modern research techniques.

Definitely worth having for those interested in the field.