This new textbook on string theory might be considered a modern pimped up version of Zwiebach's introductory course. The book is - as an introduction - better than the 2-volume set by Schwarz (Green, Schwarz, Witten), which is partly outdated, and on the same footing as Polchinski's version, but certainly not as thorough and elaborate. There is some overlap between all books (e.g. the CFT bits from Polchinski are quite similar to those in this new text, the introduction of the bosonic string via the relativistic point particle looks like the ones by Polchinski and Zwiebach, but Becker &amp; Schwarz immediately generalise the concept to p-branes, SCFTs are discussed in a similar manner as in Polchinski, and so on), but there are additional features that really add to the value of the book: all exercises within the text have solutions directly under them, so one can either try to solve them or read them through, and some parts are explained more clearly. The concepts of "(gauge) symmetries" are discussed slightly better than by Polchsinki or GSW, but for those who want mathematical proofs instead of hand-waving arguments, and more background material on supersymmetry, I can only say that I have found no books on string theory that really do that. Both are subjects of study on their own and would go "beyond the scope" of these books... Nevertheless, a very good introduction and most of all: up to date!<br><br>For mid-undergraduates, I think, the perfect sequence for string theory would be (provided one acquires knowledge of QFT and Lie algebras for the more advanced texts):<br><br>Zwiebach&gt;Becker/Schwarz&gt;Polchinski (supplemented by GSW's first volume)<br><br>But if you want to learn string theory more quickly or if you don't have problems with the very basics, then leave out Zwiebach and go for this one immediately. For graduates, Polchinski should be the start, but one can take Backer/Schwarz always as a references and supplement on some topics (connection to black holes and gauge theories).