"JavaScript: The Good Parts" was a great and a very important book back in the day. I am sure it inspired many of the improvements JavaScript has seen since then. But as it has seen these improvements, and as they were many indeed, I am not sure the book is still as relevant as it once was. Or to put it differently: There are many more good parts to JS these days compared to when the book was released :)
As others have stated, The Good Parts is no longer something I'd reccommend. It's more or less the K&R of JavaScript at this point. An interesting historical primer, but it would only serve to confuse a newcomer today, as all of the warts in the language discussed are ancient obsolete history.