Should I seriously learn QWidget?

Question

Qt

Started reading/studying the book "Qt 5.3. Professional C++ Programming", it starts with learning QWidget. But I have repeatedly heard that Qt UI is done using QML (so far, I don’t know anything about it). Does it make sense to mess around with QWidget?
Question for the connoisseurs: What is the most worth spending time learning Qt?
Prompt links to normal blogs/sites where all innovations in Qt are described.
ps I'm still learning Qt in order to create simple desktop applications for Windows.
p.s.s. I apologize in advance if my question makes no sense...

Answer 1

For mobile applications, only QML is needed. For desktop with animations and a very non-standard interface - also QML, on style sheets it is more difficult.
However, there is a large class of desktop applications for business, where animations and prettiness are not needed, but utility is needed, heaps of tables, input forms and other things - in this traditional area, widgets rule and will rule for a long time to come.

Answer 2

Quick is for beauty (design), but for "not complex desktop applications for Windows" and not only - Widgets is needed, because it is much faster to develop on it, compare how many ready-made elements there and there, and this despite the fact that on Qt in general development is comparatively slow, even with Widgets.