This book is one of the first widely available books to cover Modelica. The author Peter Fritzson has been instrumental in the development of Modelica, and the reader will benefit of his large experience and in depth knowledge of Modelica.
The author has collected and enhanced material available form other place such as the web site of the Modelica organisation. In one volume, you will find examples, reference to the language syntax and libraries, algorithm and description of some development and simulation environment. So the first benefit of the book is to be a handy single reference.
The book goes beyond just being a collection of already published material. There are a couple of chapters that provides material not available elsewhere or new light on existing ones. I particularly appreciated the discussion of Modelica packages and how they compare with Java (topics that can be confusing and generally overlooked). I also found the chapter on applications very interesting, as it shows how Modelica can be applied to other systems than the classical, electrical and mechanical ones. It would have been worthwhile to expand the examples on economics and biology. There are also a lot of useful tips on modeling techniques and the algorithm used beyond the scenes.
I think that anyone with an interest in Modelica should get the book, and currently there is no better alternative. The book would also be useful for readers not necessarily interested in Modelica but with a general interest in Modeling and Simulation, as it does cover the state of the art in this field.
I have removed a star, because I found the book confusing at times. Peter Fritzson doesn't want to overlook any aspect of Modelica, and as such even the minor or more marginal topics are covered, sometimes in some details. For example, I found too much emphasis given on MathModelica and XML representation of Modelica. I think it would have been better to leave those topics purely in Appendix and not spread them over some chapters. I also think the emphasis isn't always right. There are pages and pages that describe the flattening process to get a flat equation model from its Modelica representation. In comparison, there is actually quite little on the techniques used to solve this flat model (e.g. application of topological sort, use of biparty graph to solve dependencies between variables and equation, simplification based on the Pantalides algrorithm). It would have been worth to work a complete example through. A possible suggestion in order to keep the book small while not missing much of the material, would be to provide a CD with the Modelica library, the MathModelica examples.
Overall a very good book that provides a comprehensive coverage of Modelica and recommended to anyone working with Modelica.