1. It feels like you are underwater
2. I want ambient sound coming thru, esp when i'm walking outside/etc.
These will probably be the first Apple headphones I'll buy, and use.
On an active phone call I can carry on a conversation in the room im in 10 feet away from the person. To have that cancelled out would be interesting to try.
Also - the "transparency" mode is quite common feature of noise cancelling headphones. All of the Bose NCs have had this for years. When you seal off the ear to provide NC you need to be able to hear yourself when youre on a phone call. So its more a necessity than a "nice to have".