The one thing Qt is the most attacked for is the licensing. I disagree with this sentiment, it is pretty straightforward to me.

There are other fair criticism of Qt, more specifically about Qt Quick/QML: the need for 2-3 languages (C++/QML/JavaScript), using C++, not using modern C++, not enough out-of-the-box widgets compared to Qt Widgets, and the clusterfuck that is layouts in QML.

Out of all, the only real one for me is layouts. They are painful to deal with. I never had a problem with Qt Widgets layouts though.