The last chapter looked at objections to moral objectivism. To his credit, Shafer-Landau takes a fairly neutral attitude to the strongest objections. He dismisses many of the objections as weak, and I'm with him in most cases. Although I don't think he formulates the strongest objections at their strongest - and I think he somewhat misunderstands the argument about moral diversity - he does a pretty good job of this overall. The most important material in the book from my viewpoint takes only half a dozen pages, and I could really do with seeing the metaethics chapters beefed up considerably. But again, he writes very clearly and fairly (given that he obviously does have views of his own).
I continue to think that this is a better introductory text than the Rachels book, though the latter is still good enough to be used for an alternative viewpoint. Any student who read both would know a lot about the main issues in philosophical ethics, though they'd pick up a certain moral realist bias - especially from Rachels.
What the Shafer-Landau book won't really do is stand as an introduction to metaethics. The metaethics chapters take up far less space than the normative ethics ones, and the account is, overall, just too thin (albeit, again, better than anything we get in Rachels). I'm still looking for a really good introductory metaethics text. Most books are either too shallow and facile or much too advanced and specialised for undergraduates.