Most people that I know who have them have a dead spot somewhere. Mine is a line about 1cm tall extending across the screen.
If you have a button on the screen somewhere, someone is likely to never be able to press it.
There is a simple answer to this:
ROTATION, ROTATION, ROTATION!
Please Please Please support rotation in your applications whenever possible. If I can flip the screen around then I can get all of the buttons in any app to work.