From the reviews:
The book emphasizes techniques of two-dimensional conformal field theory as the basis for perturbative string theory. ... the book is a welcome (re-)addition to the growing collection of textbooks on string theory, and one that likely will be consulted whenever future generations return to the foundations of the subject. It is totally suited for a course in string theory straddling the undergraduate and graduate level. The occasional mathematician with a physics inclination will also find the book accessible. (Johannes Walcher, Mathematical Reviews, January, 2014)
This new textbook features an introduction to string theory, a fundamental line of research in theoretical physics during recent decades. ... It encompasses a range of essential and advanced topics, aiming at mid to high-level students and researchers who really want to get into the subject and/or would like to look up some facts. ... perfect guide for someone with some moderate prior exposure to field and string theory, who likes to get into the principles and technical details of string model construction. --(Wolfgang Lerche, CERN Courier, May, 2013)