I haven't had time to read the whole book, but from a cursory read/look at the TOC, I see:
1) We cover a *lot* more area in our book. I'm sure his coverage of his topics is great, but he covers (in my opinion) a rather narrow segment of real application development.
2) Our chapters are written by experts who work with this stuff every day. We sought out people who know this stuff really, really well because let's face it: you can't know everything. Greg Brown wrote *the* Ruby reporting library, so helped us out with our reporting chapter. David Black is an expert developer who's worked with databases and Ruby in a ton of environments, so he gave us a hand with our databases chapter. Then Assaf and myself contributed what we knew of the topic so you get very full, balanced coverage of every topic.
3) We include a lot of Ruby instruction that's simply missing from his volume. We really felt like learning how to use the language better, learn how to use the tools properly, and learn how to properly test your code are *vitally* important to making you a better developer, which is the point of our book rather than to just be an "enterprise cookbook."
I have written "Enterprise Recipes with Ruby and Rails" and I've read "Ruby in Practice" (I did not only skim the TOC). The main difference IMHO is the target audience. I assume that my readers are already familiar with Ruby/Rails and I assume that they have some experience with typical enterprise environments. For example, you'll get the most out of my book, if you often have to write applications that have to integrate with existing infrastructures. If you need to access asynchronous messaging systems with Ruby or if you have to process huge XML documents efficiently, my book is for you. Perhaps you have to use some legacy RMI services or some plain old C libraries? Have a look at my book!
You will not learn how to install Ruby or how method_missing() works. That has already been covered in many other good books.
Thanks for reading my book, but with all due respect, I really find it hard to reconcile that fact that you read it with the fact that you missed the whole chapter on Asynchronous Messaging (Chapter 7) and the whole chapter on Structured Documents (e.g., XML, JSON, YAML, etc.) in Chapter 10. We cover all of those topics, plus give you solid general Ruby skills that aren't covered in many other places.
One more small note: We also expect that you know Ruby. We say this in the "About this Book" section. As I noted in other threads, we don't teach Ruby in general but instead answer the question "I know Ruby, now what?" We teach you advanced skills that make sure that when you actually use Ruby in the enterprise, that you aren't just writing Java in Ruby but that you're writing idiomatic, solid Ruby code. So, thanks for your input! Glad to see that there's another author involved here, but I have to politely disagree with your assertions.
He repaced his skull with glass. So you can see his brain. Kinda like this tiny ad: