I actually used raw GDI+ for the GUI of an app recently. My personal requirement was that the executable had to be completely stand-alone and only a few KB in size. GDI+ helped fit the bill for creating a simple GUI and eliminating dependencies on large frameworks, so that it could easily be copied around and guaranteed to work everywhere.

Wouldn't use raw GDI+ for any UI of moderate complexity, but it was perfect for the ghetto app I made myself.