I've used it for (J)Ruby GUI development. The built-in WYSYWYG editor is pretty sweet, so Netbeans works very well as as an all-in-one dev tool for building JRuby + Swing + Monkeybars apps.
I've never used it for any Rails development, and found the coupling of the Ruby packages with Rails gems, and the presumption in the add-ons that any Ruby project was a Rails project, a bit dopey. There seems to be no way to install the Ruby stuff without the Rail stuff, though.
I much prefer using vim for development, and while there's a vim plugin for Netbeans I typically did serious editing in an external vim instance while using Netbeans for GUI stuff, or for some refactoring, which it does quite well.
For people who like IDEs, Netbeans is a really good Ruby/JRuby editor.
I've also used for several sinatra apps. Their refactoring, autocomplete, debugging and unit test/rpec is superb. Not to mention it supports Mercurial and is free, what Intellij's Ruby IDE doesn't (the core is open and free, and supports mercurial, but their ruby thing is not a plugin, and it is not compatible with the good stuff). Yeah, its a loss, but they've been neglecting it for a while, so it is sad.
Just a quick "me too" here. It's a great combination for knocking together a quick GUI around whatever random hack the business needs today. I don't know of a Swing editor that's as good.
"Second: Although our Ruby support has historically been well received, based on existing low usage trends we are unable to justify the continued allocation of resources to support the feature."
I would say, not a whole lot according to their trend analysis.
I don't agree with some of the things Oracle has done as of late, but that seems quite reasonable to me. If usage levels are quite low, then it is a waste of time to keep devoting resources to it.
Anecdotally, I don't know of a single RoR developer who uses Netbeans. Vim, Textmate and Emacs seem to be the editors of choice.
I've been using NetBeans on Linux as my main Rails IDE for the last few years. I kinda like netbeans, but I've been using it since about v4 so I'm somewhat accustomed to it.
Features I make use of: project navigation, file navigation, syntax highlighting, jump to a declaration, re-indent and very occasional code-complete (mostly for css)
Features I don't use: everything else. I always have a terminal window open with about 5/6 tabs from which i do all my generations, migrations, console, server etc. I use RVM and NetBeans doesn't seem to play nicely with that
I do JRuby/Rails development. Typically I'm in emacs (Aquamacs, actually), but I've used NetBeans occasionally when I wanted to use the debugger... beats the hell out of tracing w/ Rails.logger.
