This is what I used to jump from "I've hacked on a rails 3 app and gone through some ruby Katas" to "I am building out a full fledged SaaS product in a Rails 4 app as technical co-founder".
Highly recommended.
I, personally, just used the Rails docs, and watched DHH's introduction. The Rails guides are really good (the official guides, that is).
Pick up rails book from pragmatic bookshelf. Give it a quick read. Then watch railscast videos. Then to rails doc and gorails.
Another vote for Gorails. It's certainly the next step from beginner Rails dev to, well, not beginner.