I waited until 6.0.1 to switch to Xcode 6. Upon opening one of my project, I noticed that the quick help view of a method or variable's documentation doesn't work anymore.
For example a simple:
/*! Value of the property. */
for a @property
just causes Xcode to say 'Declared in' when trying to view the doc by option clicking on a use of the property somewhere in the code instead of displaying the documentation itself.
Cocoa's own classes doc still display fine and I can tell my documentation gets parsed as incorrectly naming a @param
will still cause a warning.