1. New perpetual calendar looks off, the font is not a font that Patek uses in other Nautilus watches. Compare the font of the date subdial to the date subdial of the 5712. Completely different.
2. The case at 9 o'clock has a noticeable pusher ruining the polished "hinge" of the case.
3. A WorldTime Nautilus would have a large button that would need to be well integrated into the Nautilus case. That's scary.