This is a fantastic book about metaethics. Metaethics is the study of the meaning of right and wrong, as opposed to just plain ethics, which purports to tell us what's right and what isn't. For example, someone might ask "Is it good to keep promises?" That's an ethics question. But if someone asks "When you say 'It's good to keep promises', what do you mean?" then that's a metaethics question.
Huemer does a great job of explaining his views clearly and supporting them with a lot of strong arguments, in a clear and accessible style. He thinks that moral statements are meaningful and are true or false just like statements about physical reality (this is called moral realism) and that we become aware of moral truths through intuition (hence the book's title). He criticizes all forms of moral subjectivism, which is the view that moral statements can be true or false depending on the speaker's, or society's, attitude or perspective toward the statement.
Huemer also does us hobbyists the favor of clearly marking the parts that are intended primarily for his fellow professional philosophers due to their technical nature and depth of engagement with the literature.
If you are interested in metaethics, or in a clear exposition of moral realism and critique of subjectivism, this is required reading. It helps if you're already familiar with modern moral philosophy -- it's not intended purely for a popular audience -- but if you count philosophy among your interests and hobbies, then you don't need to be an academic to appreciate this book.