Although we have the basics, there is a ton to do to catch up with the APM Planner.
What is most important for users, and what unique to iOS features do people want to see?
Camera control would be a great feature.
One person flying on RC and the second person could control the camera gimbal.
Match mission planning ability. From the simple single point poke to the grid autodraw system. Don't forget the integration of camera target waypoints.
Idiot Proof Setup. The calibration routines, GPS status checks and all that stuff. If any of the important things are not done it should go "mental".
As for iOS features I'm not sure they are any. Most have been knocked off partially by others now.
Features I would expect of iOS applications:
Mail - Any logs created must be easily sent (either all at once for ease or separately).
Message - Screenshots for problems or just bragging.
Google Maps - integrated as well as logs exporting
Location - iPads do not all have GPS but iOS can retrieve location from a tethered device. GolfShot does it happily for me with my iPad 2 and iPhone 5.
Can't wait for my Walrus