If you the kind of programmer that wants to know every single detail of the ExtJS library up front, Jay's ExtJS in Action book will work very well for you. If you want to get up to speed fast and fill in the details yourself, then my Learning ExtJS book is more suited. Depends what your learning style is. I cant say anything about the other books on ExtJS, as I haven't read them.
I, like the original poster enjoyed the book, but I might be biased. Lets keep it on topic, if you want to discuss licensing, there are better places for that.