I've sung the praises of Neal Adams before...but I think that many of us just can't conceive what an earthquake, what a thunderclap his arrival on the scene was.
Take, for example, X-Men #55 (1969).
Of course, it seems that not too many did pick it up, because despite some great stories and mind-blowing art, the Thomas/Adams run was insufficient to save the book from cancellation.
Soon enough, Neal would join up with Denny O'Neil for their famous Batman and Green Lantern/Green Arrow runs.
But these X-Men books, where the solid-but-staid-and-maybe-even-boring style was replaced, without warning or transition by a new, incredibly dynamic and kinetic style? That's where the revolution was, brother. And comics woulds never be the same again.