Really good? Platform-native APIs.
Qt widgets look close to native UIs but the feel isn't always the same, especially when you have to juggle with different platforms (all native widgets differ in subtle ways even when their function is the same).
(If you're on Windows. On Linux, Qt could be considered native. On Mac there is PyObjC. )
> why are you using Python?
I'm not sure
> Platform-native APIs.
are a replacement for Python?