If you just want to use Qt, I recommend PyQt / Python. But there are worse ways to learn C++ than via Qt, if learning C++ is your goal.

Worth it if you need to use a cross-platform desktop framework and don't like java. C++ is most definitely harder to use than many (newer, thus) more modern languages but you will be rewarded by the niceness of Qt.

C++ is certainly difficult, but if your expectations are mainly based on Reddit's opinion of C++, probably the language is not as bad as you think.

C++ is worth knowing, if only superficially, without any regard for Qt.

I am not sure about that. Not in the sense of gaining wisdom as would be in case of, say, Lisp or Haskell -- or even C. C++ is all just nuts and bolts, a more or less coherently implemented collection of paradigms originated in other languages. It is very useful from the practical standpoint, no doubt, but being "worth knowing", "superficially" - not so much IMHO.

Thankfully Qt doesn't go very deep into C++. I've shipped entire GUis without a single template.