"Mark up" PDFs -- not "edit"
Editing is not really the correct word. For millions of users, we simply want to "mark up" a PDF by, say, underlining a sentence. That was dead easy with Adobe Pro XI. Now seemingly impossible with DC. Constantly get image processing error messages. No customized user toolbars, as with Pro. Basically DC has been over-thought. 99% of users want the basic functionality of Adobe Pro XI.