If they've finally bothered implementing dragging and dropping of files between the host desktop and the guest vm desktop? A feature that's been requested for years now in virtualbox.
Copying files between the host and guest is otherwise a pita as you have to mess about with shared folder crap. The only way they could make it less intuitive is if you literally had to write a file to a cd on the host and then mount that cd in a separate cd drive accessible from the host.
Actually, that'd be more intuitive than the shared folder approach come to think of it. Huh, guess they can't be less intuitive then.