I've been running with the "Enable experimental error highlighting" option enabled for the last month.
It's very useful, and moves the plugin much further towards what people expect from an IDE.
I know that a lot of current focus is on type system work, and other more structural features.
However, I'd like to provide some feedback on using the nightly builds of the plugin on actual day-to-day production/maintenance work.
In our projects, we use some common Java logging libraries (log4j, slf4j).
At the moment, more than half of all the "good code red" that we see is caused by usages of these libraries.
Part of this seems to be caused by an unresolved getClass from an object:
In other cases (when also using classOf()), it seems that the plugin cannot properly determine the exact method that we're calling on a logger object:
http://youtrack.jetbrains.net/issue/SCL-2239 (seems to occur when providing an exception parameter)
http://youtrack.jetbrains.net/issue/SCL-2238 (seems to be overloading related as well)
Getting rid of this category of "good code red" would help us submitting the remaining ones, which would likely be much more interesting ;)