Yeah, just tried out the dark theme on Linux ... it's horrible!
EDIT: To be clear, running Fedora 20 GTK, it looks pretty bad, light gray on white text for package explorer.
SWT on win :P Awesome till customization required. Who said native was a good idea again for ui? I'm starting to see why Swing can be preferable. I wonder how well JavaFX does with theming.
The Darcula theme in IntelliJ with Swing looks really good.