Great reference, not so great cookbook

A very good reference on UML v2 (and includes some references to v1.4 as well). Explains the subjects very well, and as in (nearly) all O'Reilly's Desktop Quick References, it can be used to quickly jump to a relevant part and read something about the subject.

But, it is definitely not a beginners book, nor a cookbook on how to use UML! It does a decent job of explaining UML in the first two chapters, but to get the most out of this book, you need to understand the concepts behind UML (like modelling, views, etc.) and why/how you may use them to your advantage.

Overall, a decent book.