This is the same question for older version of Scala, but they say that Eclipse plugin has been improved vastly. Is it the best IDE now? How do different Scala IDE compare today?
I've been pretty successful with IDEA 9. I've briefly tried both Netbeans and Eclipse and wasn't able to get what I wanted. Eclipse's code-complete didn't behave as well as I'd have liked, and I couldn't find a way to make Netbeans handle Scala scripts; It'd just complain that the file wasn't a class.
To be clear, I've been using IDEA for a few years for Java, so keep that in mind:)