I've been using a text editor for my rails app for a while and I have a workflow that I am happy with for my existing app.
However, I am about to be starting a new app and it appears that Aptana RadRails is sufficiently developed and stable enough for use. (The last time I tried it it was in beta and wasn't quite fully baked.)
So my question is: Is it widely used in the community? What are peoples general thoughts on it?
Aptana is really good but I suppose the most widely used rails IDE is Netbeans. It supports features like CSS designing etc that aptana does not. I used to use Aptana when I was new to RoR but I have slowly migrated to netbeans 6.5. I would recommend you to try out netbeans and spend some time on it as it took me a while, personally, to like it :) .
I tried them out both (nb and aptana) and was very disappointed. Both apps are slow like hell and use way too much memory.. Aptana also crashed and showed me strange errors. IDE support in general is quite bad for Rails IMHO. There is also an extension for visual studio and jetbrains is working on a Rails IDE, maybe these will be better..
Most Rails developers seem to think that an IDE is overkill for their platform and tend to favor a more nimble approach.
This is why so many of us use Textmate on OS X. It's been the development environment of choices of not only the majority of Rails developers but of the elite programmers as well.
I would suggest to look into the unofficial port of Textmate on the Windows platform: E Text Editor.
I haven't used it but if I had to develop on Windows it would be the first thing I'd look into.
Good luck in your quest.
I use emacs, however I have never been completely satisfied with (well mixed minor modes in general) the rhtml/erb support. I had to M-x redraw-display constantly.
So on a project a few months ago, I opted to use Netbeans, and thought (with emacs keybindings turned on) it was a pretty usable IDE.
I don't know what the %'s are for who uses what. And saying which one I thought had the largest uptake would be pure conjecture.
I've tried every editor/IDE for Ruby and Rails development (at least the ones available on Windows and Linux).
Being a long time Unixer I use Vim for all the Rails development, but NetBeans is probably the best other option I've seen. It is quicker than Aptana to load, and the JavaScript and Ruby debuggers worked without any configuration. (I have a low tolerance for trying to get things working - I couldn't figure how to get Ruby debugging in Aptana in 5 mins so I just gave up)
The other guys on our team who were using Aptana have now switched to NetBeans.
I used NetBeans for Rails development. It will use alot of ram so you need that handy. I personally prefer TextMate but you need a Mac to run it.
emacs, Crimson Editor and NetBeans. I didn't like Aptana from the very beginning. Even when you create a new file, you have to manually refresh the list (seems like a small problem but after you've used nb, these bugs kinda point out...).
Now, put to the equation the plugins that nb has and the choice becomes a little bit easier!
Netbeans is really good. Check out this review: http://lifeonrails.org/2007/8/30/netbeans-the-best-ruby-on-rails-ide
The greatest Aptana feature for me is the way it parses TestUnit output so each test failure is in a different line block so you can click on each one and go through it. They call it the test unit view.
There is also a good comparison on the Aptana site http://www.aptana.com/rails
Radrails 3 is coming out and it seems to have built in some things people like about textMate ( like the tabbed code completion ) and it has built in git integration.
Its in public preview mode now. I use both textMate and RadRails. RadRails does seems a little slow and clunky compared to textMate but with an IDE you have all the other tools built in like svn ( tigris plugin ) and a console, built in debugger, etc.
I would say try out a few and see what you like best.. but don't just install and play for like 10 minutes. You need to give them a fair chance or you won't learn the little things that makes each one good / bad.
Some guys just love using emacs or vi. Personally that would make me nuts, but they've spent the time working out all the shortcut commands and building macros etc, so its perfect for them.
JetBrains claims RubyMine is the best IDE for Rails development. I agree. It has too much awesomeness packed into it for Rails developers.
The type inference, on the fly code-analysis, Rails/JS autocompletion, model-dependency diagrams, refactoring support, deep integration with Rails including HAML and SASS, powerful Javascript, HTML and CSS editing, among other features are very helpful to have while development.