Eddie is the most important rock guitarist of all time, after Jimi Hendrix. Both are of the purest breed of visionaries, blessed with the flair of genius, the irreproducible and inimitable uniqueness of trailblazers, milestones, prophets, and pioneers. Eddie was not only fast (nor was he the first to play so rapidly on the fretboard... Allan Holdsworth and Ollie Halsall had long showcased streams of unreal notes like his), he was MUCH more.
First and foremost, he was a magnificent rhythm guitarist, with perfect timing and a groove that was both infectious and expressive, explosive yet allusive, conversational. He also created a guitar sound that was powerful, deep, and earth-shattering like nothing ever heard before, despite the fact that he used extremely thin stringed instruments, not very resonant, and plucked them with an enviably relaxed touch, I would dare say serene, necessary to maintain the agility essential to his style.
Nonetheless, his amplifiers (overdriven, with tubes glowing like lightbulbs and to be discarded after a few hours of use) and the speakers (stressed to the limit by volume cranked to 10) produced a sound pandemonium over which he showed absolute control, exploiting the continuous, inevitable tendency to trigger feedback and riding it beautifully to extend and fill with higher harmonics at will any passage he desired.
Creativity would explode within him when he took solos, in a potpourri of anticipations, suspensions, octave leaps, legatos, vibratos, runs, and stops. Beyond technique, his uncontrollable and orgiastic musicality filled those stage exits with surprising, elusive, darting phrases and then here and there would pause to let everything breathe, with a sense of timing, measure, and maintenance of interest like a true musical painter, writer, or sculptor.
He certainly didn't invent tapping; Segovia also performed it, and Steve Hackett with Genesis had already penned unforgettable pages years before ("The Return of the Giant Hogweed," "Dancing with the Moonlight Night"), but he elevated this technique to a new State of the Art, and to effectively insert it amidst his intricate and rapid phrases, he adapted his right hand to hold the pick between his thumb and middle finger, leaving his index free to tap at will at the first opportunity.
Even in the use of the tremolo lever, he wasn't the first; Blackmore had already shown its expressive possibilities, but here too, Eddie raised the bar significantly. Fate would have it that Eddie Van Halen's path crossed with an extroverted and charismatic narcissist like David Lee Roth, who was far from a virtuoso, indeed a singer with precise technical limits. But in his own fantastic, irreplaceable way, he was full of himself to the point of bursting yet had a saving streak of irony (tongue in cheek, as the Anglophones say) and therefore awareness; he is responsible for directing the pure art, without ifs and buts, of his guitarist towards a genre that could be considered frivolous and dispensable, a flashy, winking pop metal that was, however, fully justified, indeed nobly elevated and rendered timeless, by the supreme quality of the guitar score, by its joy, and by its communicative power.