I just checked. You are right. The original issue of Spectacular Spider-Man Magazine was in B+W. But Issue #2 "The Goblin Lives" is in color.
It was reprinted in ASM Annual #9 in 1973 (same year as ASM#121-122 so technically it's a posthumous filler issue).
I'd say it's a gray area. It's not really been referred to much in-continuity.
Even if you don't like Mark Millar, this is the one comic of his that really has his strengths and none of his weaknesses.
I am not a fan of Millar in general, and I think it's a real pity that his worst stuff (Old Man Logan, Ultimates, Civil War) has had a bigger influence than his best stuff (MK:Spider-Man).
The artwork by the Dodsons is also great.
Most readers rate this below the classic stuff, so I can't expect the average fan to take my advice unequivocally (only 33 votes, but still).
In that regard, sorry if I'm derailing the topic, Millar's best work with Marvel is when he has someone firmly reining in his sense of cynicism. The other stuff you mentioned is generally what happens when his cynicism is allowed a freer hand to show itself, so we get ultraviolence for its own sake and superheroes being depicted as maladjusted, dysfunctional, and just plain awful excuses for human beings, let alone heroes. Of course, that stuff has greater influence with the masses and critics because "superheroes are ridiculous and terrible, anyway, and anyone who takes them seriously is a naïve, childish idiot at best and dangerously delusional at worst."
The spider is always on the hunt.