Let me make a couple of observations here. First, it is rare to find a commentator who advances either a new interpretation or at least a minority viewpoint on a particular passage who urges the reader to take his/her suggestion with caution. Bruner does just this with his interpretation of 1.7 ("This man came to be a witness to the Light, so that all might come to believe through him."). Bruner suggests that the "all" combined with "might come to believe" and the doubled "witness" points beyond John the Baptist himself, and includes John the Evangelist, especially when one considers John 20.30-31, which reads, "Jesus did many other signs in the presence of his disciples, which have not been written down in this book. But these signs have been written down to the end that you might believe that Jesus is the Messiah, the Son of God, and that by believing you can come to Life by means of this person" (Bruner's trans. adapted; italics mine; 20). Bruner also cites John 21:23-24 to bolster his arguments, where the beloved disciple is said to be the one "bearing witness" and that "his witness" is trustworthy.
Bruner concludes his observation this way:
If all this supposition is plausible, then Jesus has both a pre-ministry John and a post-ministry John--in both cases 'a witness, whose name was John.' Their mutual mission has been to move all in their hearing to believe the One in the middle. We think we will meet this second John, again anonymously but a little more clearly and particularly, when we come to Jesus' initial engagement with his first two (three, or four) disciples toward the end of the first chapter (vv. 35-42; italics original; 21)
Later, in the Historical Interpretation section, which, incidentally, I find to be worth the price of the volume alone, Bruner urges caution concerning his interpretation. He writes: " I have not found many or, really any commentators who see two Johns in our paragraph (John the Baptist and John the Evangelist), and so I advise caution in adopting my surmise" (49). This sort of humility is but just one example of Bruner's posture before the text and the history of interpretation, and should be ours as well.
Second, Bruner's prose at times is breathtaking. I find myself reading out loud to my wife at some of his more profound excerpts. Take the example of John 1:18d ("He is the One who [came down and] explained [God])," which Bruner labels "The Classic Interpretation of God." He writes:
The Greek word for "explained," it will be noticed, is the root of the English word 'exegeted,' which means 'interpreted.' Exegesis is the science of the interpretation of texts. Jesus of Nazareth is the invisible God's authorized exegete and exegesis, God's authorized self-interpretation and self-explanation. As we know, a biography is the story of the life of a person by another person; an autobiography, on the other hand, is a person's self-explanation and self-interpretation. Jesus, the eternal Word of God in the flesh, is God's Autobiography. We would love to know what God is and who God is and what God thinks, wants, does, and is like. Jesus explains. 'God the Only Son' exegetes (italics original; 40).
Again, this is a small sampling of some of the hallmarks I have found in this work so far, namely, humility, great writing, and profound insight.