By every account I've seen, it's a great book and the only reason I haven't read it is that I've already been bitten by all of JS' pitfalls once or twice :)
The real reason I'm posting a comment, though, is to give you a link to the JS Jabber episode in which they talk to Dave about the book:
http://javascriptjabber.com/044-jsj-book-club-effective-java...
That episode will give you a good idea of what the book is like.
It's also fairly comprehensive, ranging from - some evilness (type inference with ==, eval and its performance toll) - functions and higher order functions - objects and prototypes. Some good explanations of the all prototype and constructor thing - array, dictionnary and some things to know about their prototypes - api design and concurrency
It's 200 pages full of content, I recommend it.
Your invocation of Effective Java made me look for Effective Javascript, and it does exist. Amazon users give it five stars: http://www.amazon.com/Effective-JavaScript-Specific-Software...
Can anyone comment on how well this books fulfills the expectations implicit in a book calling itself "Effective X?" Or just how effective the book is with respect to accepted javascript practice?