Steve Jobs managed to do a lot, far too much to list here, before his all too early death. He brought an uncompromising vision of what personal computing should be, and his ability to actually execute on that vision was what made people talk about his "reality distortion field"[a]: By sheer will-power, Steve bent reality itself and made the impossible happen.
But that indomitable will to shape the world came with a need for control, and if I were to name the greatest mistake of Steve Jobs, it would be his inability to give up control. Apple's products, and Jobs's vision for computing, depended on a walled garden approach with Apple in charge, to avoid compromising the vision. With Jobs in charge, that walled garden had a benevolent dictator; with Jobs dead, who knows what the garden will be like in the future? Will the next dictator be equally competent and equally benevolent? What about the one after that?
Real-world dictatorships may occasionally produce great things and may be very ordered, clean and stable, but history tells us that democracy and freedom, while chaotic and difficult, tend to produce systems that scale better and last beyond the life of a great leader.
Steve Jobs built something great, but he couldn't transcend the need to personally control it, and therefore what he built didn't reach its full potential. Jobs, as CEO, had every right to maintain tight control over his own company. Jobs, as a visionary of what personal computing should be for you and me, should have been much more willing to let go and accept that if his vision is to outlive himself, then he has to accept that it must be made our vision; with all the compromise and disorder that entails.
I wonder what Apple users will do now that Jobs is gone. Will they wait for the next CEO of Apple to pick up the torch where Jobs left it, or will they pick it up themselves?