I avoided purchasing this book initially due to the length and negative reviews posted here. In hindsight this was a huge mistake. Here are some points to consider.
1. This is NOT a book for experiencd programmers. This is a book for novices who want to learn programming using the python language. If your coming from another language, try Mark Pilgrim's Dive into Python 3 or a python cookbook. If you are wanting to do something specific, find a topic focused introduction - e.g. Natural Language Processing with Python.
2. The length of the book is from the conversational explanations. Yes it is longer than, say, Mark Summerfield's Python 3: A Complete Introduction. But I can tell you from experience, it reads much, much faster. I find myself FLYING through this book, without having to re-read things seventeen times just to understand what is going on. Keep that in mind.
3. Most of the example code is very simple. Some have complained about this, but there is a very, very big advantage that is overlooked by most of these people - it is very easy to jump around to different sections and not feel lost. I tried doing that in another book and ran into "Remember the 100 lines-of-code example we started 3 chapters ago? We'll continue on with that to show how x function works." No thanks - I just want an explanation of function x please.
4. This book is focused (mostly) on Python 2. If your just starting out, Python 2 is what you need as of August 2011. Most 3rd party libraries and tools still work mostly (or exclusively) with python 2, and it will likely continue to be this way for some time (ex: Django does not support python 3 yet). Don't make my mistake and assume if you know Python 3 you will be able to convert to 2 when needed - the converse is much more practical. If you dont specifically need something from python 3, it doesn't make sense to learn it right now.
5. This book is probably too big to carry around with you day-to-day. That being said, you can always upgrade to an e-book version from O'reilly at significant discount when you already own the physical book (5 bucks I think).
With that in mind, this may or may not be the right book to start with. If not, consider:
1. Learn Python the Hard Way - if you like a hands on approach, with examples that build on prior ones
2. Dive into Python 3 - if you are already have programming experience
3. Python 3: A Complete Introduction - if you want a thorough treatment of Python 3, and have programming experience.