It's much, much better than it used to be but it is still not as good as the Java support. I write both in my day job and while I much prefer scala, anyone who feels that IntelliJ's scala support is equal to java is deluding themselves. At least a few times a day I come across something where I start shaking my fist at the IDE over something which would Just Work for java.

That said, it is improving and closing the gap rapidly.

Perhaps you're using more of the IDE features than I am. I spend most of my day in IntelliJ writing Scala code (and a bit less maintaining old Java code) and haven't spotted any major issues with the features that I use.