In light of recent news I decided to port over some of my AIR for Android demos to iOS. Apple developer registration process aside, I was surprised at how easy it was to publish the same apps for both platforms. The code for all three examples worked unchanged from the Android optimized version. Here is an overview:

The Good:
Same code works on both devices!
Develop iOS apps on a PC.
Performance is good for simple animation and logic.

The Bad:
Box2D tanks through the exporter even with GPU acceleration, 17fps iOS vs 30fps Android.
File size is crazy big, my demo went from 3KB to 7MB.

The Ugly:
Registration for iOS development is a pain in the ass.
Exporting from Flash for iOS takes significantly longer than Android, minutes instead of seconds.

General Observations:
Colors differ slightly between the devices, iOS is lighter than Android.
Resolution through the exporter is currently locked at 480 by 320, which will hopefully change soon.

Summary:
The exporter works well for simple applications but don’t expect to get real life physics. Performance on native AIR for Android is significantly better. The savings you’ll get from developing once and deploying to multiple devices is HUGE. Just make sure your expectations are on par with actual performance or you’ll be re-coding in Objective-C.