Let's not start pretending now he was a particularly likeable person. Many who worked with him found him unbearable. But he changed the face of music to a remarkable degree, not just a member of the massively influential Velvet Underground but probably the most influential figure in the band. He managed to take influences, both musical and literary, that were then well outside the sphere of popular music and run with them. And the results were never affected or self-consciously artsy but powerful and gutsy. (His maxim was “one chord is fine, two chords is pushing it, three chords and you're playing jazz.”)
He made music truly rooted in the place that spawned it, downtown New York. (Brooklyn-born, Reed was the native New Yorker of popular song.) It kicked off the Seventies years early, when most were barely able to keep up with what was happening in the Sixties. And, though in their brief and tempestuous history the Velvets only made four albums, they were so wildly different from each other that subsequent bands have made whole careers out of copying just one of them. I love the Beatles and (in their heyday) the Stones, but most of the music I listen to now has more of a Velvets influence than both of those put together.
His subsequent solo career was admittedly uneven. Perhaps due to his drink and drug habits, though I also suspect he was enough of an egoist to imagine whatever he did must be great. But the highlights among them... well, not much is higher. Consider - 'Berlin', 'Metal Machine Music', 'Street Hassle' and 'New York.' (Curiously, spaced out fairly evenly rather than coming in a block.)
There's no point pretending I can throw up something quickly that could do all of this justice, because I can't. Should I ever get the time to pursue my inclination to write something about my all top 50 albums, it will almost certainly include a Velvets and one of his solo albums.