I hate Ruby on Rails. I love Ruby. But I hate Rails. If this is for a job get the book I suggested. If you just want to learn a MVC framework look elsewhere. Django or CakePHP are good starts.
Let me start by saying that I love Ruby. I love Gems. I just find shat RoR scales poorly. Even a simple app on my local machine feels slow. Look at Twitter a RoR app. And Digg is PHP. I would like and use and love Rails if it scaled and even was somewhat snappy on small sites.