Address book syncing is the main issue. I want my contacts on my phone. So taking phone calls gets a bit awkward, though with Siri getting a little better it’s sort of doable.
Other than that it’s the constant re-typing of destinations from the calendar.
Here’s a fun tip I learned recently - you can press the share button on your phone and send the location to Tesla. This makes copying addresses from calendar or anywhere super easy
And yet it still makes borrowing a Tesla a pain.