See, here's the deal. I'm not a very advanced IDE user. I used Eclipse for years and JDE before that, and I wouldn't ever have considered myself a "pro" with either. I learned what I needed to get the job done and not a whole lot else. Beyond that I never knew some of the coolest features, and was never so good at convincing people to make a switch. This actually has helped my migration to NetBeans, since it basically does all the things I was used to in Eclipse. But it has been problematic when I try to convey how cool the new NetBeans Ruby support really is.
It's super cool. It does things I've not seen any other IDE or editor do.
However, it's best not to take my advice, and Roumen Strobl has recorded two seriously excellent demonstrations of Rails and Ruby support in NetBeans. They make the sale way better than I could (though I now have many good ideas for how to sell it better in the future).
If you have any interest in Ruby editors or IDEs, you should take the time and watch these, especially the Ruby support.
Two Demos: JRuby on Rails and Advanced Ruby Editing in NetBeans!