Carson and Moo have thoroughly reworked this book, removing or revising Morris' contributions and adding much new material for the second edition. Some sections are rearranged, and there are a few entirely new sections. I read the original book straight through a few years ago, and I haven't found anything else that does quite as good a job of staying on top of the current scholarship while defending generally conservative evangelical views on the authorship, date, setting, purpose, and other backgrounds sorts of issues on each NT book. I expect the updated edition to be equally thorough and more up-to-date on recent trends in NT scholarship.
Particularly of note is the section on the New Perspective on Paul, which Morris and Carson have both been on the forefront of interacting with (from a more traditional perspective in both cases, though both have been willing to acknowledge that we have learned something from the NPP). They call this section brief in the introduction, but it's 11 pages, a fair amount of space compared to how much room they give to most topics. They have also provided a lengthy addition covering the history of interpretation of the NT, from the early Christians to contemporary biblical scholarship. They've also expanded of added more on the content of each book, something reviewers complained about in the first edition, and there's also a little bit on the social science approaches to NT studies, something that wasn't very far along in the original book. All in all, the new edition sounds as if it should be excellent.
They've removed the dust jacket and replaced it with a visually appealing cover on the book itself, and they've increased the margin size significantly, both of which suit its primary use as a seminary textbook. They list the intended audience as seminary students in the first and second years, but a studious enough person can read it for profit without the additional seminary background. I read the entire first edition without any seminary training at all. It's certainly not the level of detail a scholar would want for an exhaustive treatment of every issue, but the bibliographies and footnotes can provide further reading to get exactly that, and it would be ill-suited for students if it tried to do too much.
This has been the standard evangelical NT introduction for quite a while, and as of the revision its place will be secured for quite a while.