I like this book even better than "The Good Parts". It contains very good examples that show specific aspects of the language. These examples combined with associated explanations makes this book clear and very informative for me. What I like especially was the structure: short 68 problems with explanation, analysis, and examples. Also, not very long (~200 pages). If you can choose only one of the books described in this post, read this one.
Can you recommend some of them? Share your opinions in comments.