Anderson gives a truly evenhanded review of the last few centuries of biblical scholarship on John, as well as suggests many new areas of study.
More study has been focused on the Synoptics recently, not to mention the claims of Thomas and Q, or the now mostly discarded idea of Gnostic redeemer myth, than John. Most liberal scholars of the last century held that John was the least historical, least accurate, least early, of the gospels, and had no real claim to have been written by John.
Yet John is cited--arguably--as early as 1 Clement, about 95 AD, and Ignatius, about 110 AD, and is actually the gospel apparently most in use among early Christians, at least to judge by the fact that there are more fragments and papyri of John than any other gospel.
Anderson goes through all the various streams of research into John, citing their weaknesses and their strengths.
He finds that "where the great promise of critical scholarship has been its objective neutrality, the historical treatment of John comes across as less than that. When John's material is deemed different from the Synoptics it is excluded; where it is similar it is related to a derivative relationship to a non-Johannine source" (p 89).
For example, Anderson explains how Bultmann's approach "falls flat when tested on the basis of its own evidence" (p 77). Bultmann imagined that a "Theios Amer (a miracle-working God/Man) mythic construct prevalent in the contemporary social milieu would have affected" (p 90-1) the story told about Jesus.
Most problematic here is the timing. The Gnostic myths came later than the gospels. Nor does a possible influence mean an influence. Nor is it plausible that Second Temple Jew would use Hellenistic myths. On the contrary; it is clear John heavily uses the Old Testament and typological figures there--never Hellenistic myths.
Furthermore,it is also possible to see the Johannine Jesus as a "wisdom-imparting sage...Jesus not only brings divine wisdom; he is the Word and Wisdom of God: (p 94) as well as the "institution -challenging cynic" (p 94).
As for John's composition "the most plausible and least speculative of Johannine composition theories involves a two-edition theory of composition inferring that first edition of John was finalized around 80-85" ( p 78). And he argues that "The unreflective notion that religious typological ideas were simply taken over by Gospel traditions...is too simplistic. Religious typologies....were applied to interpretations of Jesus' ministry...because they made sense" (p 36).
Nor does he agree with the idea that the differences between the Synoptics and John suggest isolation by the author of John. Instead he proposes using "cognitive criticism...(which) examines the relation between the ministries of the purveyors of Jesus and their presentations of Jesus' ministry" (p 37).
One very helpful addition to this book is the way Anderson gives a review of all the strengths of one stream of scholarship versus the weaknesses of the same arguments, as detailed by later scholars.