Right from the start, I was impressed with the writing of the book. The topics followed a natural progression that made it easy to understand where you came from and where you were going. The tone of the writing is conversational yet authoritative and most concepts are explained very well. Related topics, such as Ajax, are discussed succinctly and effectively so that the focus remains on the Ext JS library.
One of the most difficult things to do with a multi-author book is to maintain a high-level of quality and consistency throughout the book, but Learning Ext JS does an admirable job of smoothing out those rough edges. There are subtle tone and style shifts as chapters change from one topic to another, such as the notable increase in puns and wittiness in the middle chapters (for a good chuckle, focus on Chapter 8: Ext JS Does Grow on Trees), but the explanations are still just as clear regardless of which author is on the keyboard.
Overall, I found Learning Ext JS to be one of those rare technical books that truly understands it audience and what it’s trying to communicate. Most of the points are very clear and well-explained, and I learned a lot about the advantages of Ext JS in comparison to other major libraries. The widgeting system is truly impressive and this book does a great job at walking you through that system to create rich application interfaces. On top of that, it was enjoyable to read with a lot of information packed in. If you’re looking to learn about Ext JS, this is a great book to pick up at Amazon.