This v28 marks the end of the immersive feeling a Folio could offer the user. In stead of having a truly full-screen experience, there's always that iOS7 system bar in sight. At least, that's what I understand from this documentation. So there's no way to prevent users to be distracted by anything unrelated in their screen. That's a real pity !
Some might think this is just a trivial change with eventually minor impact, but I think being able to present content over the whole screen is a crucial factor in distinguishing a Folio from other publishing formats like a web page.
Does this requirement also affect other apps like e-readers or games ?
Note that this system bar appears only when you tap to display the navigation bars. The top bars require 64 pixels instead of 44 (or 128 instead of 88 on iPad 3). When the navigation bars aren't displayed the designed still covers the whole area. Displaying the system bar is an iOS 7 requirement.