The hard bound book is a pleasure to read. Weinberg is an acknowledged master, so there is always something new that one learns from him, even though there are so many other good texts on quantum mechanics. His introductory history chapter is very instructive, like a similar chapter in his QFT books. The treatment in the rest of the book again shows the characteristic thoroughness of his writings.<br>I only wished he had used Dirac notation for convenience of students,though by not using it, he has removed the widely prevalent misconception that Dirac notation is a must for abstract formulation of QM.