Just an initial scanning of the PDF so far. It will take days to go through it all. It took about 20 years for it all to be originally published. (counting the AD&D originals being part of that 20 years)
Copy-Paste the text listing of page numbers where each book starts in the document. There is no such list at the beginning and you will want that to go to the correct book rapidly.
I saved that as an OpenOffice word processing document in the directory (file folder) with the PDF.
I titled it "Entire collection of all 26 AD&D Second edition Index of books"
Lack of this index and hypertext linking it to the books' title pages is the only thing I can find to complain about really. That's not enough to downgrade the rating.
PDF is hyperlinked which is really nice. Monstrer manual alphabetical listings, click the creature name and it takes you to the creature.
Few if any of the original pictures appear to be in the PDF. Though they did put in a color picture for each creature.
Appears to be the original text based on my memory. I have been playing D&D since 1975 Lost all original books in a fire.
With recent developments at WotC/Hasbro I am considering going back to 2nd Edition.