I currently intend to use SFML for my next game project. I'll need a substantial GUI though (RPG/strategy-type) so I'll either have to implement my own or try to find an appropriate third party library, which seem to boil down to CEGUI, libRocket, and GWEN. At the same time, I do not anticipate doing that many advanced graphical effects. My game will be 2D and primarily sprite-based with some sprite animations.
I've recently discovered that QT applications can have their appearance styled so that they don't have to look like plain OS apps. Given that, I am beginning to consider QT a valid alternative to SFML. I wouldn't have to implement the GUI functionality I'd need, and I may not be taking advantage of SFML's lower-level access anyway. The only drawbacks I can think of immediately are the learning curve for QT and figuring out how to fit game logic inside such a framework after getting used to the input/update/render loop of traditional game libraries.
When would an application toolkit like QT be more appropriate for a game than a traditional game or multimedia library like SFML?