I used to read this cover to cover when I first learnt bash. But I later found that its advice can be subpar from time to time. There are better resources in learning bash.
Sorry, not going to go into details here. But I think the statement is not controversial. There’s probably well written criticism on it somewhere.
But then it wasn’t a bad starting point. I don’t have a better book to recommend. There are wikis with better info. But not in the form of a book which is also free I think.