I've had to work on PyQt5 at work, and was pleasantly surprised out how easy it was to hack up a full app.

I was using PyQt, and I found it nice (Qt's integration is good).

It goes out of its way to not rely on the STL, so that std::string and QString are separate, non-convertible classes. QList and std::list<> are the same, same for QMap and so on and so forth. So data communication is already a pain.

We then have further issues with function invocation. Slots and sockets are simple with python, because functions are first-class in python. In C++, they are very much not, so slot-socket binding looks like: connect(sender, SIGNAL (valueChanged(QString,QString)), receiver, SLOT (updateValue(QString)) );

This is less than ideal.

STL wasn't always here and still isn't in some embedded platforms.