But nothing beats it.
I just spent some time tonight doing the IDE dance -- every once in awhile you have to go through all the long forgotten development environment options to see if you're missing out -- and I'm still where I am 2 years ago when I first purchased RubyMine: there is nothing else like it.
Aptana Studio 3 still sucks (it finally got SCSS support, though), NetBeans is terrible as always (and is apparently being discontinued, no surprise there), and I still don't have the MANLY STEEL required to set up vim for Ruby/Rails and stick with it.
So, RubyMine for the win (again). In a few months I'll be purchasing my, what, third license for it? I hope they keep up the steady development pace.