This book would be perfectly fine for anyone unfamiliar with the cognitive ethology field in general. It does a fine job of introducing the idea of animal intelligence, what was known of it at the time, and how it is known. The biggest strength of the book, in my opinion, is the fact that it carefully lays out how each experiment was done and illustrates every step of it. This is vital to anyone interested in the field and just beginning to familiarize themselves with it. I think this book, with its easy to read layout, and thoroughness, would be of interest perhaps to a young adult who wants to learn more about animals? It's fine as an introduction, and it is by no means a bad book. It simply wasn't a good choice for me personally.
My problems with the book mainly lie in the fact that it was so deeply monkey and primate centric in its studies. After having done a bit of a deep dive into books on animal thought and behavior I was delighted by learning about how many studies had been done in truly unexpected areas. Archerfish, orb spiders, guppies, cichlids, rock ants, tardigrades, and water striders have all been studied and shown to have the rudiment behaviors of personality (boldness vs. shyness) and intelligence to them. To focus primarily upon chimpanzees is to do a disservice to the sheer breadth of the field... and to focus so heavily upon chimpanzees without even broaching the concepts of animals having spirituality (e.g. the waterfall dance) and deeper emotions also seems a bit of a waste. It's one thing to claim animals are intelligent, it is another to explain why this may be, and to extend beyond the simple idea of cleverness to the concept of self.
I was further disappointed in the book's failure to acknowledge certain behaviors that had, at that time, been acknowledged rather thoroughly. The book cast doubt on the signature whistles of dolphins, but never acknowledged the problems with the studies of Koko which are fairly well known in the field. They also failed to acknowledge the naming calls of ravens and parrotlets in the wild, both of which are fairly well known to researchers. They didn't acknowledge the understanding of syntax that both parrots and dolphins have shown rather handily either. The intelligence of more 'common' animals was also ignored - in particular dogs, cats, wolves, cows, chickens, and pigs were fairly handily ignored...
The book didn't quite do enough for me. It's a decent introduction, but little more.