I went through the Ruby course, Rails for Zombies I && II, and thought they were fun and intuitive. However, the main things that I retained were how rails works such as migrations and generations. Being new to frameworks, the "auto-magical" aspect behind all of this was fairly confusing so I guess that's not a bad thing to walk away from. Your question is, however, for Ruby itself, and I have to conclude with saying that although it was entertaining, I didn't retain much technical knowledge of Ruby.