Here I am at the third day of the Advanced Rails Studio in Dallas. Dave Thomas, Chad Fowler, and Mike Clark have done a nice job with sharing their knowledge with us *and* encouraging the audience to share with each other. DT, CF, and MC are pragmatic, skeptical, funny, and sometimes surly. I really enjoyed that they are not Rails “fan boys”. They don’t pull punches. If something in Rails or Ruby bothers them, they are going to let you know. 
Coming into the studio, I thought it would mostly hands on labs for three days. Instead, the labs were provided as preparatory and evening exercises. The actual time of the studio was spent with a mixture of high level discussions, sharing best practices, and some how-tos.
Should you attend? Well, it depends. What are you looking to learn? The price of the studio probably will factor into your decision as well. I would recommend asking lots of questions to people who have attended to see if it is right for you.