Porting from Qt 4.x to Qt 5

Has anyone ported a Qt 4.x application to Qt 5? We are going to port some software that uses Qt 4.8 extensively. We use the Core, GUI, Network, OpenGL, Test, Webkit and Xml libraries and our software is available on Windows, OS X and Linux.

If you have experience porting Qt 4.x applications to Qt 5, are you having any specific problems?