AI is a field crowded with specialist sub-topics, each with their own jargon and methodology. Without getting bogged down in specific areas, this book is a good attempt to cover the general historical and philosophical background of AI, and a helpful reference to the main controversies and unproved hypotheses which are bound to come up whenever you look into a particular area of AI application.
There could be more on Chomsky and language, more on robotics, and more on, well nearly everything, but isn't that the sign of a good book if it's trying to be an overview? You want to know more. In my opinion many extended AI discussions (particularly speculations about the future) do not examine their basic assumptions and Brighton & Selina's book is a good place to start if you want to know where you're starting from.