The ever-helpful Review of Biblical Literature has published Raymond Collins’ review of Witherington’s book:

Ben Witherington III
$amz(0830829318 Letters and Homilies for Hellenized Christians: Volume 1: A Socio-Rhetorical Commentary on Titus, 1-2 Timothy and 1-3 John)
Reviewed by Raymond F. Collins

Collins is generally accepting of Witherington’s work despite their disagreement on authorship.

I’ve read the introductions and various other portions of Witherington’s section on the Pastoral Epistles and can recommend it.