He is really only notable because he is being pushed by media because he happens to be black and he doesn't mind putting himself out there. He's not even in the top 25.
There is Elizabth Blackburn, Ashoke Sen,Alan Guth,Michael Levin....ect just a few of many that have actually done something.
He is more of a media personality than a scientist. He's mostly know for taking work others have done and make easier for regular people to understand and not for actual work in the field making discoveries or advances. Not that what he has done isn't important, making science more accessible to the masses is a good thing but on pure scientific achievements he really doesn't have much to show. He is kind of a much more educated and qualified "Bill Nye the Science Guy".