This edition of Effective Java was released over 4 months ago, which means by now there are likely 8 zillion reviews of it. Nevertheless, I'd like to present my thoughts on this book.
As a very experienced Java programmer, I was somewhat reluctant to pick up this book, as I thought there wasn't much more I could learn from a book like this. I was wrong. I'd say most of the advised items were not new to me, but it's always good to see a concise reminder of base principles and "Effective Java", as it were. However, there were also numerous items that were very much new to me, and were very enlightening. In the "I've got to find something wrong with it" department, I found one advice which although completely correct, could lead some people astray because of some details it left out (http://davidmichaelkarr.blogspot.com/2008/10/stringbuilder-is-not-always-faster-than.html).
The book is divided into eleven chapters, divided by subject area, like "Creating and Destroying Objects", "Methods Common to All Objects", "Generics", "Concurrency", and "Serialization", and others. This edition is well revised from the first edition (published in 2001). It not only added new chapters relevant to features new in Java 5, it revised items where the advice clearly needed to change, and it even removed some items that had become obsolete.
Many of the advices are a single page, but many of them go into great detail. Item 8, "Obey the general contract when overriding equals", is 12 pages long and covers everything you need to know about correctly implementing the "equals" method for logical equality. This item only barely mentions the "hashcode" method, usually discussed at the same time, as it covers it thoroughly in the very next item.
The most surprising content (to me) was in the last chapter, on Serialization. The effort required to ensure secure, reliable, and maintainable serialization was mostly lost on me before reading this. This chapter not only went into great detail on how to resolve most serialization issues, but it also showed many examples of nefarious code that could be used to compromise serialization code that was not secure.
In short, I would recommend this book to any intermediate to advanced Java programmer. You are certain to gain a better appreciation for the details of producing better and more effective code.