Intellij IDEA isn't so bad as an IDE (it's faster and less buggy than the Eclipse Scala plugin last time I checked), but SBT is utterly horrible. It's so awful I'd literally strongly prefer to use Ant (ie clunky scripting in XML) instead.
I suspect the awfulness of SBT is causing a lot of harm to Scala adoption.
http://blog.jetbrains.com/scala/2013/07/17/sbt-plugin-nightl...