This is the central location for the Pestalozzi Bibliothek Zürich (PBZ) system, and it shows…read more Three floors of books, one floor just for friendly check-in and automated check-out, and a central location. It's referred to as the "Altstadt" branch in the PBZ literature and website.
I'm not sure I'd consider the "café" area much of a cafe --- as far as I can tell, there's tables where it's OK to eat, and an automated Nescafe machine. "Library café" usually implies the option for a slice of cake to me.
I do like that there's a bit of a kid's play area downstairs, near the kid's books --- but it's not much of one (certainly smaller than the kid's room at the library in Boulder, Colorado where I spent so much time).
All in all, when the Höngg and Altstetten branches don't have the book I'm looking for, I turn to this one.