If I regularly read blog posts and essays written about Bitcoin, would this book be worthwhile? If not, what audience is this book targeting?
"Learning..." For beginners
"Programming" For intermediate-level
"Mastering" For advanced-level books
The "animal" books have the line-art drawings of animals on them. O'Reilly has other series, including books on general audience topics. There might be other key words indicating the level of the book if it isn't a programming book, but that's the nomenclature behind Programming Android
I would expect this book to go deep on bitcoin.
Some, particularly some of the language or OS books, are reference-oriented. Not the kind of thing you'd necessarily read straight through.
Some, the "intro" books, are just what that sounds like. Enough material to get started.
I don't know if I have any O'Reilly books I'd consider "deep", exactly, but I don't think they really aim at that.
In general, my experience is the books are what the titles say they are.