Requirements sought: Easy to use library for creating user interfaces, works with Python
Experience with PyQt
I used PyQt4 and chose not to use IDE for designing user interface. Getting first application up and running with examples provided by Riverbank was easy and it was easy to expand from there to my roguelike. Creation of new widgets (UI-components) was easy. I was using composition and not doing any custom drawing on screen. PyQt feels fast, but I did not do any performance testing.
API is not very pythonlike. It has been built to look similar to regular Qt API, so adapting Qt tutorials and resources is easier than if they had chose to redesign the API.
PyQt is good set of Python bindings for Qt. Big amount of examples and tutorials available is good.