So I've been a long time CLI programmer. Most of the IDEs I've tried didn't fit my tastes or come up short in various ways. Especially for Ruby. Particularly because Vim has become so clutch for me it's been hard to migrate in good faith to an IDE…Until now.
For a few weeks now I've been giving RubyMine a shot. It's primarily a Rails IDE but they've done a fantastic job at keeping it generic enough to work with any Ruby project in its tools. I've been using it for both.
Pros: One of the things that I really liked was the integration with vim. It was very comfortable for me immediately. It comes with all of the bells and whistles you'd expect from an IDE. You get the built in explorer, debugging console, collapsing code segments, and even color selectors in line for your html. The built in integration for RVM I found particularly nice. It's also very friendly for using git. The refactoring and auto keystroke features are not intrusive. Also, it seems to have the timing perfect for looking up methods. It has a great deal of plugins available to it as well as a pretty good community surrounding it. They keep up to date with the latest technology, which for me is important. They're likely to be the first and best IDE for Rails 2.0 support and already support 1.9.x fully. I like how it saves files in real time as you edit them, but ultimately if you don't save the file it reverts. This makes testing fast and easy without writing files. One of the very nice features is the way it integrates debugging with irb. When the debugger fires up it opens an IRB environment for where the debugger paused. You can do all the things you expect from a debugger like GDB and additionally you can in real time insert lines of code. I've found this to be extremely powerful for testing. It takes the development cycle down to one pass often as you get to the bottom of problems.
Cons: I found it to be somewhat heavy. But here's the deal. I tested it on both windows and linux. It did better on windows. I suspect this is because on linux I'm using open JVM. It runs okay for me, but there are times the graphics seems to lag slightly. The default "skin" it uses for fonts and the way it looks is a little dated. It's very simple and for some this may be their first choice. I wanted a smoother look with slightly darker syntax highlighting. It costs $99 dollars.
I highly recommend this IDE for someone using Ruby in earnest. It's elegance is in its power. It's not intrusive and it feels, to me at least, that it gets less in your way than other IDEs I've tried out. They have student and open source developer licenses as well as commercial licenses.
I have tried the demo, and it seems like a great IDE. Certainly worth the price that they are asking for it. I've been trying to decide between it and E - Text Editor for the last week or so. E is a lot cheaper but obviously lacks some of the features of Rubymine. Of course, that might very well be a boon considering that I don't particularly like heavy IDEs. I think I prefer to use Rubymine but I'm not sure that I would get a hundred bucks of use out of it. I do very little programming in a Windows environment, so it might be a bit much. In nix I typically do all of my work in gEdit, in windows I have been using Notepad++. Bah I can't decided which one I want! :P