I think our book stands out because it answers a question that few books actually ask: "I know the language...now what?" Very rarely are there practical thoughts given to what you can actually do with a language. Usually you're fed arbitrary code examples with little relation to what you'd actually use the language for. In this case, though, we spent a lot of time making sure that we teach you how to get things done in Ruby.
As for actually learning Ruby, I'd recommend Manning's "The Well Grounded Rubyist" (coming soon) or my free Ruby book
http://humblelittlerubybook.com. The former will obviously be much more in depth, but if you don't have the cash for it, then please enjoy the free book!