He does read and respond -- but I never write about personal issues -- only brief suggestions to broad issues or opportunities. Though in my work exchanges with CEOs are common so have practice keeping it clean and direct.
He's been forthcoming in giving a heads up that a particular suggestion is in the works.
I only do it on occasion, and his predecessor Kellner was also good about it.
Really hope people don't abuse the privilege and think carefully before writing the question "is this something that could improve things for a large number of flyers?"