Elementary Psychology or First Principles of Mental and Moral Science Book

After looking over some of the reviews here on goodreads about this book, I had to admit I found them somewhat amusing. After doing some research on the people who rated this book poorly, it would seem that they just don't comprehend the usefulness of this book.
I used this book as a companion piece for reading classical, modern, and contemporary essays by "the greats" in moral philosophy. Perhaps, the best way to use this book, and one I would strongly recommend for those who didn't get it, is for that purpose. As an example, and I use this example, because I think this is the source of much of the poor ratings, I read St. Augustine's essay's Of the Morals of the Catholic Church and The Enchiridion . Then I read St. Aquinas' essay's Summa Contra Gentiles and Summa Theologica . I followed these two classics with a modern reading of Soren Kirkegaard's The Journals, Either/Or , and Fear and Trembling . I concluded with a contemporary reading of Philip L. Quinn's God and Morality . At the conclusion of these readings I then read chapter four of this book, Does Morality Depend on Religion .
It is only within the understanding of these writings, and then reading the chapter in this book, that the usefulness of the information becomes clear. This book summarizes the complete doctrines of, for example, Divine Command Theory, Natural Law, and the overall presumed connection between morality and religion. Along with this, it shows the problems associated with these systems of morality/ethics.
All of the moral/ethical systems presented by this book are also exposed to criticism. For some of the ethical systems, the criticism becomes either to hard to overcome, or needs further clarification to be a workable system. Keeping in line with the examples of Chapter four, a serious defect and insurmountable objection comes to Divine Command Theory and Natural Law. It is this inability of these ethical systems to overcome the objection that I think exposes the true reason for the bad review of this book.
Overall, I have nothing but praise for the book, and I think it is important to also take note in the fact that the book does not make claim to which ethical/moral system is correct. It only shows the various systems and elements of them (hence the word "element" in the title). Will this book tell you what is wrong or right? No. Can this book be used to highlight and critique elements of ethical systems? Yes.
Perhaps, if you have an interest in moral philosophy, and really want to understand it, then this book is for you. Enjoy the journey.