Except writing Qt application on Symbian^3 was like stabbing yourself with a needle every second. Nokia never bothered to fix QWidget on the Symbian platform and just told developers to wait until QML's Qt Components were ready. And, of course, Qt Components for Symbian^3 wasn't stable until after Nokia already announced the transition to Windows Phone.
Maemo did a good job of implementing QWidget (including kinetic scrolling), but they threw all that out in MeeGo when they decided to drop native support for QWidget and have everybody just use QML instead.
And don't get me started on how Intel confused everybody with their version of MeeGo.