Infants have a lot going on in their minds. More than the general public tends to give them credit for. As both a developmental researcher and a parent with a young infant, it was nice to read this wealth of information in a format that was easy to digest and easy to see in my own child. This isn't really a book on how to raise a child, but the information and ideas in the book should help you relate and respond better to your infant. I suspect that some people will be surprised at how much is going on in their infants brains, while others will feel that this book is saying (in specific terms) what they already know: behind those bright big eyes is a very keen and active brain that is busy learning about the world.
In a nutshell, infants are born with a degree of internal capacity (innate/evolved); traits that work with the environment to help the infant learn fundamental information at a phenomenal rate. Things like faces, places, physics, movement, etc. all need to be learned (to various degrees). Infants are proving to be far more sophisticated learners than we ever thought, mainly because developmental psychologists are getting better at finding clever ways of measuring babies' cleverness (e.g., you just can't ask a baby if it knows that 1+1=2, but you can see if it's surprised by a new toy when there shouldn't be one- that shows counting and memory). In fact, the brain's neuron count (thinking cells count) peaks right at the end of infancy. The adult brain is certainly faster and more accurate, but never again will a human have the flexible potential for learning that they possessed as an infant. What Gopnik does is further extend these fascinating findings to the hypothesis that we are who we are, as individuals and as a species, because of our infancy. Our infancy is not just a building phase, it also shapes and constrains us. The way babies think can reveal important insights on the nature of thought and how adults think. It's an ironic twist, using babies to teach adults, but for the most part, I think it's very well-argued.
Overall then, if you're interested in infants, or about the nature and development of human thought, I highly recommend this book. It's pitched at a general audience, so parents, grandparents, and those who work with infants should have no problem learning more about the delightful little learners they spend their time with.