Third in the top-10 relates to annotation parameters.
We're configuring the component graph for our projects using spring, and are using annotations like @Transactional.
At the moment any annotation parameters (like "readOnly" for @Transactional) are marked red in IntelliJ.
Even worse, completion and Ctrl-P ("parameter info") for annotation parameters seems to be totally absent, effectively sending us back to the Dark Ages of Manual Typing ;).
I think this is covered by http://youtrack.jetbrains.net/issue/SCL-2142
Given that modern-day frameworks (Hibernate, JPA, Spring, etc) expect a fair amount of annotation metadata, this issue is a day-to-day annoyance.