If you are looking for a book to take your Java beyond the basic, this is definitely one worth working through
First off, a disclosure; I have a - small - personal interest in this book because I worked with one of the authors for a while. I hope this does not cloud my judgement - though that is, of course, for you to decide.
Unlike many other Java books on the market, this one does not attempt to teach you the basics of the language in the first few pages. This is laudable - usually these micro-introductions are at best useless.
Java in Practice is obviously not intended as a first book on Java; but once you are familiar with the syntax, you should put this book high on your list, even if you are an experienced OO programmer. Java is in many ways a deceptively simple language, especially if you approach it from a C++ background, it has its own subtleties and requires familiarity with its idioms to be used effectively. This is where the book excels; much as Effective C++ highlighted the most dangerous and tricky areas of C++ and provided idiomatic solutions, Java in Practice gives detailed advice on how to make your Java applications run faster and be more maintainable. For example, it gives valuable advice on such micro-level techniques as typesafe constants, immutable objects and proper exception handling strategies. In addition, it also discusses higher level techniques such as creational patterns and balancing performance with resource requirements.
Of course, some of this material is quite basic and most of it has been covered before in other sources; but I have not yet seen another Java book that makes it so accessible. Admittedly, I personally found the style a little chatty at times, but that is a matter of taste. If you are looking for a book to take your Java beyond the basic, this is definitely one worth working through - and the summary of the recommendations in the appendix will make it a handy reference afterwards, too.
The fact that it is much thinner than Effective C++ probably has more to do with the language?