I am currently teaching a special course on issues of New Testament Introduction at Talbot Theological Seminary in La Mirada, California (LA area). Besides the hype that is surrounding the NBA Finals, my time has been spent reading Bart Ehrman's The New Testament: An Historical Introduction for this course.
This volume is one of the most popular texts for early Christianity classes in the USA, which is why we are discussing it in the class. It is clearly written and engaging. It summarizes many commonly held positions that are held about the Bible and New Testament in some scholarly circles. It is important to know what generations of college students are being taught in the name of knowledge and understanding. I am discovering that it is what Ehrman does not mention that is often important.
For example, in treating the authorship of the gospels (all of them), he does not address any of the external evidence for authorship that comes from sources like Eusebius or Irenaeus or any of the canonical church lists. This is historical evidence and ignoring it prejudices his volume's work, cutting out one of the two key factors one has to address in treating authorship, namely external evidence for a work's authorship. Vincent Taylor and C. E. B. Cranfield regarded such evidence as decisive in treating this question in terms of Mark's gospel.
I am quite aware that many think the internal evidence is against such an authorship claim for Mark (and Ehrman does present those arguments). Those arguments can be addressed. So given a fair debate over the issues that lead one to think about who wrote a gospel, here is a point the claim Mark did not write the gospel has to deal with. What commends Mark as the author, if we are going to simply pick someone to enhance the reputation of a gospel when no one supposedly who knows the author is (which is what the alternative view claims is the situation)? What is Mark's reputation? He failed to survive the first missionary journey and caused a split between Paul and Barnabas according to Acts. So how does randomly attaching his name to the book enhance that gospel's credibility? Such a theory does not work here. Mark's reputation, such as it was, on its own does not enhance the credibility of the work. More than that, the tradition also consistently associated Peter with Mark, so why was this gospel not simply called the Gospel of Peter, if one is free to name any author the church could choose? Given a choice between Peter and Mark on the basis of reputation, Peter would be the obvious choice. Something else must be at work, namely, a tradition careful about who it called an author, naming someone who in this case had an otherwise less than stellar resume. Arguments like the ones I just noted go completely ignored in his volume (and these are fair historical questions). So user beware that if you are being asked to use this text in a college class, some key points are not even being raised.