This is the most concise, yet thorough, description of Python I have found among a half-dozen of the most highly-rated books about Python. It is thorough, yet to the point. It covers aspects of Python not found in any of the other books (I found the online version of this book by searching for such a topic, but wanted the physical book). Guido van Rossum is the author of the Python Language, so he is the definitive source for information about Python; and his books are very readable.
This book is very readable for anyone who is experienced in another language. Although Python itself may be a good first language, this book is a bit too concise for someone learning a programming language for the first time. For such a person, I would recommend "The Quick Python Book" by Harms and McDonald ("Dive Into Python" by Pilgrim and "Core Python Programming" by Chun are also good).