The best part of the book is Turing Machines, where the authors introduce the notion of procedures that makes it several times easier to design Turing machines and get a feel of their power. Further, the authors seamlessly establish the equivalence of different models viz. Turing Machine, grammatical computability, and recursive function theory.
Book is overall good but you will face difficulty in understanding concepts as the language used is hard and concepts are not cleared. I just opened this book for just 2-3 times till now. Prefer some Indian author's book.