From the point of view of teaching Saussure's famous (and obscure) Course in General Linguistics, this is a good book. It is particularly well developed, even for the "For Beginners" series. With a little concentration, one should emerge from this book with a basic grasp of Saussure's linguistics. Further, the book briefly touches on Saussure's influence on later thinkers such as Levi-Strauss or Derrida.
The book disappointed, however, in answering (or failing to answer) the question, "What is it all FOR?" I shall try to expand briefly on this:
Saussure defines a "sign" as "anything that tells us something other than itself". For instance, "the jagged line on a graph isn't there to make you think about jagged lines; it's there to show sales going up and down". It was Saussure's view that such signs derive their meaning from their relationships to other signs. He gave the example of a chess game. All the pieces (the signs) form a system, and it is the interaction between the pieces, or their relationships, that creates their value.
Supposing, then, that we should apply this to a philosophy of life. Saussure's system of signs could show how people make sense of their world by the value they attribute to various signs. Further, all of these signs would hold meaning only insofar as they related to the whole system. Or supposing that one should desacralise religion, and reinterpret it all in terms of signs -- one would have a whole new way of looking at religion.
This is an excellent book, yet the relationships between Saussure's linguistics and various other systems of meaning are not brought out well. This is arguably what Saussure has become most famous for.