Part of the Advanced Language Series, this is a revised edition of "The Greek Dialects" published by Chicago University Press in 1955. Its virtues were comparative clarity and conciseness on a subject too often treated, for example by contemporary work in German, with prolixity and obscurity. It became the standard scholarly introduction and reference work on questions of dialect; and though much valuable additional work has been done on the subject since its appearance, it largely retains its original virtues and still provides a valuable starting point of reference.
The Advanced Language Series reissues important books on Greek and Latin Language (and associated areas) which have been unavailable for some time or have not previously appeared in readily affordable paperback format. They are intended for the reference shelves of all scholars and students of classical languages.
Still the first port of call in matters of the Greek dialects from the Archaic period to the Koine, and while 1955 is a long time ago (it would be another year before the decipherment of Linear B was officially published, for instance, though Buck mentions it in a footnote and seems to have a fair knowledge of it already—given the book's focus, it's not clear it would have made a great difference anyway), content-wise the first half still broadly holds up, and any issues are more a matter of omission than of error: in keeping with the fashions of the era, the focus is almost entirely on phonology and morphology, with only a very brief mention of syntax and none at all of vocabulary. While those are also the most interesting bits as far as I'm concerned, it has to be acknowledged that that's a genuine gap. (Structure-wise Buck is to be commended for at least having a proper table of contents and following the treatment from the point of view of the various sound correspondences and inflections with a section from the point of view of the specific dialects as a kind of inverse look-up—linguistics before, say, the 1970s produced some truly heinous walls of text, and Buck absolutely deserves credit for trying to avoid that.)
The second half of the book, however, is an overview of certain inscriptions in various dialects that even in 1955 must have been seen as academically inadequate: they're all rendered in "modern" mixed case with accents and macrons (macra) and spiritus with no or ambiguous indication of the original alphabet and very few annotations—that is, heavily reconstructed texts lacking heavily in credibility. The point is obviously to demonstrate rather than prove various features previously discussed, but the great feeling of ambiguity often gives the appearance—just the appearance!—of circularity. Doing things this way is a deliberate choice informed by an unwillingness to overload readers who don't want to care about the various alphabets and other epigraphical complexities as well as typesetting limitations (also felt keenly in the appearance of ϙ if not ϝ elsewhere), but the balance struck is not good.
Carl D. Buck's THE GREEK DIALECTS: Grammar, Selected Inscriptions, Glossary is the standard handbook for understanding the world outside of Attic and is an essential resource for the classicist or Indo-Europeanist.
The grammar is divided into phonology, inflection, word-formation and syntax. In the phonology section, Buck simply lists each Proto-Greek phoneme and how it varies in each dialect. In the section on inflection, he sketches the ramifications of phonological differences in noun declension and verb conjugation. Ditto for the section on word formation. "Syntax" for Buck mainly means differences in the uses of the cases and verb moods. What is most helpful about the grammar is that he lists the peculiarities of each dialect. This enables Greek students trained in Attic to know what to expect before they approach a work in Ionic, such as Herodotus. The second part of that work, dealing with inscriptions, shows what evidence we have for each of the Greek dialects.
The real drawback to Buck's work is its age. Last revised in 1955, it predates the understanding of Mycenaean data gained by the deciphering of Linear B, which somewhat importantly changes our view of the dialects. He also wrote before widespread acceptance of laryngeal theory, which complicates the issue of differing prothetic vowels. Nonetheless, in spite of its age, THE GREEK DIALECTS is a book worth making use of. Now, if only some modern scholar could make the necessary updates...
This is the best English introduction to Greek dialects, and the BCP has kindly reprinted it for 21st century readers. It is accessible to students with a good knowledge of Attic Greek, though it is best used in conjunction with a class on Greek epigraphy or dialects. Other resources are useful companions, like Meiggs-Lewis' book of inscriptions. Keep LSJ handy, and be prepared for new vocabulary! Buck is a reference book I'll be coming back to for years to come. From a grateful student.