The World's Largest City does deliver on the promise of its title. The problem here is the quality of the PDF scan.
What you see in the Full-Size Preview section of the listing? That's the quality of the scan throughout. Useable, but not crisp or as clear as it ought to be.
The scan was not made from the original book layout; in fact this PDF looks like a hand-scan. Some of the pages are slightly askew, the contrast and crispness of the scan could be so much better than it is, and the book's cover image isn't even included as part of the scan.
Again, it's all usable (see the preview) but it's disappointing -- even slightly insulting -- that a $40 PDF couldn't be created with better quality, or more care for the customer.
Still, publisher AEG appears to have essentially abandoned D&D gaming as of this writing, and the book is generally out-of-print as far as I can tell. Unless one wants to pay $80 to buy a physical copy of The World's Largest City from AEG's website store, this is your best bet for owning a copy.
Short version: the book delivers on its promise, but the scan quality as of this writing is mediocre. Functional, but far from professional.