As a high school student, I read his "Mathematical Discovery". Then, as a freshman, I met my future adviser (A. A. Goldberg) and he recommended "Problems and Theorems in Analysis", saying that this book is "the basis of all his (Goldberg's) scholarship". For many years, he had a seminar for undergraduate students based on this book (in Lviv University, in 1970-s). He was a great practitioner of Polya's teaching methods.
Later I bought 3 volumes of Polya's collected works, and still looking for the 4th volume. Polya substantially influenced my own mathematics, and I am especially proud of proving one of his conjectures. I regret that I never met him personally.
But only concrete problems attracted me in Polya's books. His general considerations on "how to solve a problem" I always found boring, and never really read the second part of his "Mathematics and Plausible reasoning".
That's why I am very skeptical about a "course on problem solving" with any theory of "problem solving". I think one can learn solving problems only by solving concrete problems.