You may also wish to read some readers' opinions, Mathematica user group comments, and customer reviews on Amazon.com.
Regarding the Numerics and Symbolics volumes, in Mathematics Book Reviews, SIAM Review 49 (2) (2007), by Willy Hereman, Colorado School of Mines:
"The GuideBooks offer a staggering number of original examples, creative applications, and engaging exercises. Often, I succumbed to the temptation to work on some of the many problems."
Regarding the Numerics volume, on ZentralblattMATH by Matti Vuorinen:
From the Introduction:
"Damit [durch die vier Mathematica GuideBooks] wird insgesamt die Anwendung der
Mathematik auf klassische und moderne Probleme in Wissenschaft, speziell in
Informatik, und in der Visualisierung nicht nur beschrieben sondern deren Durchführung auch außerordentlich erleichtert ...."
"So [through the four Mathematica GuideBooks] is the application of mathematics to classical and modern problems of science, especially in computer science and computer graphics not only described, but extraordinarily made easier..."
Regarding the Symbolics volume, on ZentralblattMATH by Matti Vuorinen:
"Every computer science, mathematics, physics, engineering library should have this four volume set on its shelves, because this is the best source of the applications of Mathematica to numerous computational tasks."
On MAA's Mathematical Sciences Digital Library by Marvin Schaefer:
"The Mathematica GuideBook for Programming provided this reviewer with insights into solving and visualizing problems by using Mathematica rather than the other way around. Its wealth of exercises, annotated solutions and integrated bibliographic references should make this set a valuable part of the library of any Mathematica user. I highly recommend it."
Regarding the Programming volume, on ZentralblattMATH by Matti Vuorinen:
"This book is one of the most valuable sources for the advanced users of Mathematica. Because Mathematica is now used in all mathematical institutes, all the science/engineering/computer science/mathematics libraries should have this book and its companion volumes."
Forthcoming in Computeralgebra-Rundbriefe (currently downloadable from the author's homepage, PDF)
From the Introduction:
Der hier zu besprechende abschließende vierte Band ... kann wohl ohne
Übertreibung als das zukünftige Referenzbuch für den Einsatz von
Mathematica schlechthin bezeichnet werden.
Mit Blick auf die Fülle des didaktisch gut aufbereiteten Materials ist
das Werk auch weit über den Kreis der Mathematica-Nutzer hinaus
interessant als Fundgrube von Anregungen und Beispielmaterial, ...."
The here-to-be-discussed fourth volume ... can probably be designated
without exaggeration as the future reference book for the employment
of Mathematica. With a view on the abundance of the didactically well-prepared material, the work is of interest also far beyond the circle of
Mathematica users as a source of suggestions and example material....
Mathematics Book Reviews, SIAM Review Volume 47, Number 4 pp. 799-858 (PDF), by Willy Hereman (Colorado School of Mines); Bob O'Malley, Section Editor
From Conclusions:
In the same spirit, Trott's GuideBooks (at an economical price of $79.95 each) are a gift to the scientific community. Certainly, I see the GuideBooks becoming
an invaluable, lasting resource for aficionados of Mathematica. Whether you plan to use these books for teaching, research, or recreational purposes, Trott's passion for Mathematica is contagious. I encourage you to go play with the Mathematica "tools and toys" in the GuideBooks!