As a professor and former compiler writer, I'm a big fan (and owner) of compiler books (including those by Aho, Ullman, Goos, Waite, Wirth, ...). The last years have seen a resurgence of really good books covering modern compiler engineering. This one (first and, gladly, second edition) is by far the best in its class. The contemporary competition consists of
* Aho/Sethi/Ullman/Lam: nice book, great follow-on from the earlier dragon books, but is so thick that it's tough to teach from, and to be honest, it's getting convoluted.
* Allen/Kennedy: another great book, covering some of the best results in optimization (of well behaved languages like Fortran). It is, just like the latest dragon book, heavy slogging and not digestible by many students.
* Muchnick: yet another excellent book, but it hasn't (AFAIK) been updated.
By contrast, this book (Cooper/Torczon) is not only digestible (nice presentation, not overly terse), but it also covers new and interesting algorithms and data-structures. This applies not only to today's hot topics like optimization (and related data-structures like SSA) and code-generation, but also to front-ends. For example, the chapter on lexical analysis covers Brzozowski's minimization algorithm. (As a specialist in such minimization algorithms, it's very encouraging to see compiler writers/text book authors now embracing such an easily taught algorithm.) All in all, a very nice book on modern compiler engineering.