Skilled work with difficult texts
While no translation of an ancient text or group of texts can be called "definitive," the translations that Bentley Layton presents in this book are certainly among the best available. The historical introduction to Gnosticism that precedes the texts is a very helpful, easy-to-follow summary of a lot of complex doctrines. His introductions to individual texts are extremely helpful.
In a graduate Coptic class, we are currently going through the "Gospel of Philip," one of the texts included in this book. A translation by Wesley Isenberg is also included in James Robinson's "The Nag Hammadi Library". We are reading the Coptic, but because of the multiple interpretations of the text that are possible at many points, we sometimes consult published translations such as those of Layton and Isenberg. As I have compared these two translations, I have found Layton's to be more interepretative. That is, he takes a stand on which of various possible meanings he prefers and clearly expresses this in his translation. He does this based on his own extensive knowledge of Gnostic literature and of the type of Greek literature from which the Coptic translations were made. He explains this clearly in his introduction. Thus, one may from time to time disagree with his interpretation, but one will know that Layton did not make his choice on a whim, but based on a profound knowledge of the background of the texts. He has produced a translation that is readily accessible to members of the general public as well as to scholars, and he has provided enough background information to help non-scholars see where each text fits in the Gnostic view of the universe. However, in so doing, he has not overwhelmed the reader with the masses of detail that could be included from the considerable scholarly work on the many Gnostic texts.