It does read like it was written in a hurry, being a trove of unredacted Gygaxian prose with minimal copyediting for 20th-century syntax.
The rules are sort of interesting just in they fact that they exist. They're 2D6-based rather than
D20. I guess it could be hypothetically similar to OD&D's D6 Chainmail stats, but haven't really scrutinized it for such.
In any event they are one more incarnation of the game, a footnote but with implications. During the time that TSR was exploding onto mass-market shelves, it remained a small independent company, resisting whatever corporate sellout offers it presumably received a the time. Soon it would reign in licensed modules published by other companies such as Judges Guild, becoming even more insular.
Yet somehow they agreed to let another publisher [Troubador Press] put out an alternate version of the rules with the title "official" right there at the top of the cover. Official AD&D no less, a rules system TSR was still in the process of completing with the
DMG that same year [1979].
So the first complete version of Gygax' AD&D wasn't technically the one published by TSR, but the one included with the coloring book. Obviously the notational system used by the Acaeum & all other collectors is in error & must be corrected immediately.
Troubador Press' 2D6-AD&D is henceforth AD&D 1st edition, & should probably receive a new forum board [above Collecting General-TSR, to be entitled Collecting General-Coloring Books].
TSR's AD&D is now corrected-2nd-edition [1977-1987] & corrected-3rd-edition [1988-1999]. 3.0 is unaffected since it's still the 3rd edition of D&D [woodgrain box to 1990s Mystara supplements = D&D 1, AD&D = D&D 2, Hasbro D&D = 3].
Please begin altering your ebay listings to reflect the above changes at once. Compliance is mandatory.