Well, for starters, if I'm using a map app on the CarPlay/Android Auto dashboard, then I expect phone calls to not cover the entire screen automatically, as I'm probably using the map for navigation.

Anything on top of that would just be extras, but something basic like that should work at least. Which it does on Android Auto, but not on CarPlay.

The biggest shock for me moving from Android Auto to Carplay was the complete lack of multi touch support in Apple's offering. Worked perfectly on Android.