You get three pdfs in the package; one for the Guide, one for the Glossography, and one for the maps. The books themselves are text that has been OCR'd, not just a scan of the pages, and are quite nice and legible.
The maps are at once nice and frustrating. They're given at full size, which is great, but as they seem to have been photographed rather than scanned, the creases on the maps are very visible and give a slightly bowed effect (and a lot of glare) in the places where they're not completely flat. But the most frustrating thing about the maps is the fact that they're presented on two separate pages in the pdf, rather than put together as a single image. Given what they are, it's doubtful that anyone is going to find having to flip from one map to another particularly useful, and it robs them of their grand effect as a gorgeous unified whole.
Still, on the whole that's a minor quibble, as anyone with a decent pdf editor will be able to put the maps together the way the Gods and Gygax intended. The fact that the boxed set is now available is a huge plus, and at $9.95 it's a steal even if you already have the hardcopy like I do.