Although you'd be able to make one yourself, with all of the editing programs around you could draw directly on the graph paper using a tablet and stylus to keep a digital copy rather than needing to print it out. This isn't to say it's a great deal, inspite of how cheap it is, but it does have its uses.To be fair, you do get 130 pages of hexes or 44 pages of graph paper in your PDF for that $0.99
The PDF from January 2016 is the "Original Edition Premium Reprint" that WoTC released in November 2013. The new PDF is a scan of a sixth or seventh print of the original version. The Premium Reprint was recreated using the same print, so the content is almost exactly the same, although the Premium Reprint PDF includes the Reference Sheets while the newer PDF doesn't.This is a little odd. The original three-volume set has been added...except its already been on drivethrurpg for quite a while. However, the cover is different so I guess this is a different printing.
Dungeons & Dragons Three-Volume Boxed Set
Here is the one that's been there since Jan 2016, in case you're curious.
OD&D Dungeons & Dragons Original Edition
Most of the hobbits and ents have been replaced, just not all of them. On pages 8 and 9 of Men & Magic they are halflings, but on page 6 they are still hobbits. That would make it a sixth print, except that page 9 of The Underworld and Wilderness Adventures also has two hobbit references, which it shouldn't if this is really a sixth print. I could only find ents on page 33 of Men & Magic; all the other references were to treants. My best guess is that this is Frankenstein scan of a sixth print of Men & Magic plus a slightly earlier version of Volume III. A bit moot now, given that it has been taken down.I can confirm that. I was able to buy a copy before it was taken down.