You have no idea how bad it can get. I hate hate hate anything Ruby. Rails itself is a good idea, but you basically get 0 editor support even with tooling and you barely know the structure of your objects.
If you stay away from metaprogramming in your own code Rubymine brings a lot to the table:
Go to definition (all the way down to any source code in gems)
Usages
Refactoring (renaming methods, classes and filenames)
Integrated debugger
It even infers types now
Brings nice documentation for methods if you use RBS and/or Yard
I think this goes as long as it can be taking into consideration that Ruby is dynamically types and has a lot of support for meta programming.
I know of Rubymine and use it daily. Rubymine sadly gives up if files get too large, which is realistic for `config.rb` even in medium sized Rails projects.
But I wonder if a language can be considered good for use if you can only really use it within a dedicated, non-free IDE.
