This still seems to me to be an excellent introductory ethics text - I continue to prefer it to the similar book by James Rachels, though someone starting out in this field could do worse than reading both about the same time. They cover a lot of the same territory (Shafer-Landau must surely have been influenced by Rachels), but where they differ Shafer-Landau usually seems (to me) to be better. E.g. he offers a much more sympathetic, and I think superior, discussion of contractarianism. Rachels also wrote an excellent introductory textbook, but was too often guided by his own personal and contestable views.
That said, I find the metaethical discussion rather shallow and naive. E.g, the sophisticated relativist theories of such people as Gilbert Harman are not discussed at all. I realise that Shafer-Landau has written separate books on these issues, but I don't think he has done justice here to anti-realist or relativist views. There's still room for someone to put together a better textbook than this.