If you already know the language flow control you don't need to read paragraphs of a book to relearn to how "think" in the language. You just need the "whats new" parts.
I'm not confident how deep the impact of the new features is on thinking in the language. I can learn the new features, but I fear I'll still be essentially writing C++03 with C++17 bells & whistles. Did the semantics and idioms change much?
(I hear the compile times are the same though -.-)
If you already know the language flow control you don't need to read paragraphs of a book to relearn to how "think" in the language. You just need the "whats new" parts.