This module has been replaced with Empty Fields. Empty fields is similar but stores the empty configuration with the view mode, allowing more flexibility. You should go there instead.
Field Empty Text adds an "Empty Text" configuration option for any field. The module behaves similarly to a Views "No Results Behavior", displaying a configurable message when a field is empty and configured to display.
To configure the empty text for any field, visit it's Edit page -- the same place where you configure the field label.
If a field is empty and configured to be displayed in a view mode, the translatable configured empty text will display instead of the normal behavior (the entire field/label not being displayed).
Field Empty Text plays nicely with Features, as the configuration is stored in the field instance configuration.
Token Support is added as of 7.x-alpha3.