The best RoR book... but don't buy it...,
This review is from: Agile Web Development with Rails 3.2 (Pragmatic Programmers) (Paperback)
This is one of the best RoR books (if not one of the best computer books) that I've read.
Very clear explanations, creating a genuinely impressive website in just a few short steps, with explanations on what's going on. As a long-term Microsoft developer, new to all this command-line stuff, it was a breath of fresh air.
The problem.. Ruby on Rails is moving so fast that even though this is one of the newest books on the subject, even the April 2011 version is out of date. Using the latest Ruby downloads, files are no longer stored in the same "standard" place as they were a year ago, some of the commands have subtly changed, filenames have changed, etc.
So, I would recommend that potential buyers SHOULD buy this book, but buy it from Pragmatic Bookshop's own website. They do actually keep it updated there, so for about £16, you get the latest Kindle, PDF and epub versions. And they'll even email you when there's a new update, or send it to your Dropbox account.
(Just to show a little less bias, I wish someone would update the "Ruby on Rails for Dummies" book. This was also an excellent book, extremely clear, but most of it's info is five years out of date.)