The first review copy I received from Packt was Drupal 6 Themes. I was pretty unimpressed by that title and decided not to review it, since I didn't have much good to say about it. However, the Drupal 6 jQuery book by Matt Butcher is something else!
The book has everything that you expect from a jQuery/Drupal book, and it delivers it in a clear and understandable way, and it goes in depth into the topic. The whole book revolves around doing things the Drupal way, and using best practices. I also appreciate that the author always uses code in a way that maximizes the use of Drupal's core and it's popular modules, he explains how you can make use of Drupals jQuery behaviours, and there is a cool example using Drupal's AJAX capacities in combinations with a Views2 JSON view.
The book delves deep into the usage of jQuery in themes and modules and there is interesting stuff in there for developers of any experience.