Multivariable Mathematics represents an admirable attempt to integrate the study of multiple subjects fundamental to applied mathematics which usually follow introductory calculus, namely linear algebra, multivariable and vector calculus, and differential equations, including sections or chapters on systems and stability analysis. It makes sense to combine these subjects given how deeply intertwined they are, and there are excellent more recent attempts to do so, such as in Gilbert Strang's new text Differential Equations and Linear Algebra. The book also possesses a strong pedigree, being an indirect descendant of a classic vector calculus text from the 60s and 70s by Williamson et al.
While the book does to some extent present a coherent overview of the topics, it has too many shortcomings for me to recommend it unless one is in absolute need of a single volume on all the included subjects. First, topics are often poorly motivated. Second, important results, techniques, concepts etc. are often introduced deep in the middle of examples; the text jumps between the informal exposition of example problems and a semi-formal definition-proof format seemingly randomly and with little regard for the actual distinction between theory and application. Third, the book often exists in an uncomfortable middle between formality and informality, with the shortcomings of both but the benefits of neither, although there are exceptions, such as in some of the linear algebra material. Finally, the book contains a fair number of errors, particularly typesetting errors which are mathematically misleading, and the included solutions are often extremely unhelpful or have poor figures.
The book definitely has its merits; at the highest level the integration of the various topics is arguably successful, and there are moments when what the book could have been shine through, but overall I can't recommend it to a student trying to learn this material.