This book takes me back! It was actually the book that got me hooked on reading programming books!
Ryan Bigg (who wrote the original Rails in Action) was a regular in the Rails chat room.. which I kept going in to ask very basic questions. One day he said Aston, why don’t you read The Well Grounded Rubyist? If you do I PROMISE YOU that all these questions you’ve been asking you’ll have been able to answer yourself, and then some! (Or something to that effect!) He wasn’t wrong, after reading that book I really did feel like a well grounded Rubyist 
The book featured in my Best Way To Learn Ruby and Rails blog post, and this is what I said about it:
I was totally hooked on this book when I first picked it up, it just made so much sense. I was also extremely impressed (and grateful!) with how David A Black explains every bit of code he includes – that’s such a big deal because it stops you from losing morale or feeling stupid. David is a real life teacher (it shows!) and the little touches and thoughtfulness in this book make it shine.
If you really didn’t want to do the three previous (Ruby) steps, you could quite easily jump right in here as this book covers the basics well – but try not skipping any steps if at all possible! This book’s not just about the basics either – it covers a great deal, spread over 15 well paced (and highly enjoyable) chapters.
It’s great to see it is still being updated!