I've started finally writing some scala at work, so was happy to have the excuse to pick this book up. Scala's an interesting language, and one I'm definitely still learning. This book certainly helped, and I'm sure I'll return to it as I'm actually writing code and thinking about how to organize my work.
This book did a pretty good job of introducing the language and walking you through many aspects, including some features you may or may not need (xml processing, parsers). As I read it, I was thinking about a fun alternative format for the information, sort of a graph of "cards". Each card would be a tidbit extracted from the text, probably with many cards coming from a chapter or even section. After you read a card, you'd be presented with a list of questions, and whichever matched best what question you had ("what's really going on here?" or "is there a cleaner way" or "what would it look like in Java") you would click on to get taken to an appropriate card. You could then track back to whatever point and say "ok, show me the next one", and maybe the system would keep track of what you've seen to know what to show next. At some point I realized that using the REPL was probably just as good as this setup though :)
There were a few points where I found the book to be a bit too quick (or maybe it was just my reading). A mysterious @ operator (or something) made its way into an example, well before another instance with an explanation, and not into the index, and appeared without comment. Later, example code included nested traits, which seem like a thing that could bear some explanation, probably in the chapter on traits, though that didn't seem to be there.