Been an Apple user since the late 70's, a Mac user since 1986 (my parents bought a Mac Plus). I owned the public beta of OSX and some developer pre-releases prior to that, and was a beta tester for 10.6 (Snow Leopard) and various Quick TIme releases.
I agree with so many others - he is the Edison of our time really. He and Woz and the team created the personal computer and personal computing, he redefined it in his second go-round at Apple, redefined personal music devices, redefined smart phones, and redefined the tablet. And, talk about bipartisanism - Obama, Boehner and Cantor all agree on the impact he had. And the tech giants and rivals also agree - Gates, Zuckerberg, Page, Schmidt and Brin of Google, Hurley and Chen of YouTube, Samsung's Choi, and others. That shows how much of an impact he had on the industry.
Genius doesn't even start to cover it ...