There are some valid points in this book, but the author is woefully ignorant in the field of comparative psychology, and repeatedly makes claims that simply aren't borne out by research. He claims, for example that humans are the only species in which adults engage in play, although he allows for the possibility in cetaceans. This is entirely inaccurate. He also claims that humans are the only species that exhibits compassion for unrelated individuals (although, again he holds out the possibility of cetaceans, for which he apparently has a fondness), a concept that is also belied by any number of studies of altruistic behavior in other species. I appreciate that Comparative Psychology is not his area of expertise, but for the sake of credibility, it would have been prudent to do at least a cursory review of current research before making such broad claims in a field he's unfamiliar with. The fact that he wasn't willing to take this most basic step to ensure the accuracy of his claims makes the reliability of his other premises suspect.
In addition, he makes claims based on his own opinions, rather than on empirical data, claiming, for example, that all humans find learning and accomplishments useless unless shared with others. His characterization of his friend hitting a hole-in-one on a golf course "disastrous" because he was alone on the course speaks more to the author's insecurities than to anything else. The author is, of course, entitled to his own opinions. The issue is that he presents them indiscriminately as facts.