In the recent issue of JETS (Dec 2006), Dan Wallace reviews Bruce M. Metzger and Bart D. Ehrman, The Text of the New Testament: Its Transmission, Corruption, and Restoration (4th ed.; Oxford: Oxford University Press, 2005). The full review is available here.
Wallace brings up a number of critical points:
1) the plates are of lower quality and now interspersed throughout the book;
2) the section on Important Witnesses lists only eighty Greek manuscripts (a mere increase of three);
3) the discussion of internal evidence is underdeveloped (examples in the discussion of 1 Thess 2:7 and Mark 16:9-20);
4) the critiques of other viewpoints are too irenic (for example, Fee's arguments against rigorous eclecticism are not mentioned)—this is a lingering deficiency from previous editions;
5) the revision is uneven—a clear demarcation between Metzger's contribution and Ehrman's can often be seen, close to the point of internal contradiction;
6) "other errata are sprinkled throughout the book" (especially the indices need numerous corrections);
7) the discussion of the future task is too thin.
On the whole, however, Wallace appears to be less critical than D.C. Parker in his recent review of the book in JTS. Wallace ends his review on a positive note:
"Lest the casual reader think that these criticisms outweigh the strengths of the fourth edition, let me reiterate: Metzger-Ehrman's Text of the New Testament remains the standard handbook on NT textual criticism. Even with its few flaws, this volume should be read, underlined, digested, and quoted by all students of the NT text. It rightfully deserves to be within arm's reach of all who study the sacred Greek Scriptures."