Walter Issacson writes in HBR six months after his biography of Steve Jobs came out:

The essence of Jobs, I think, is that his personality was integral to his way of doing business. He acted as if the normal rules didn’t apply to him, and the passion, intensity, and extreme emotionalism he brought to everyday life were things he also poured into the products he made. His petulance and impatience were part and parcel of his perfectionism.

One of the last times I saw him, after I had finished writing most of the book, I asked him again about his tendency to be rough on people. “Look at the results,” he replied. “These are all smart people I work with, and any of them could get a top job at another place if they were truly feeling brutalized. But they don’t.” Then he paused for a few moments and said, almost wistfully, “And we got some amazing things done.” Indeed, he and Apple had had a string of hits over the past dozen years that was greater than that of any other innovative company in modern times: iMac, iPod, iPod nano, iTunes Store, Apple Stores, MacBook, iPhone, iPad, App Store, OS X Lion—not to mention every Pixar film.

For Steve Jobs, the meanness always justified the ends.

What Issacson considers to be Jobs' keys to success:

Focus. "Deciding what not to do is as important as deciding what to do."

What are the 10 things we should be doing next?” People would fight to get their suggestions on the list. Jobs would write them down—and then cross off the ones he decreed dumb. After much jockeying, the group would come up with a list of 10. Then Jobs would slash the bottom seven and announce, “We can only do three.”

Simplify. "Simplicity is the ultimate sophistication... It takes a lot of hard work to make something simple, to truly understand the underlying challenges and come up with elegant solutions."

Take Responsibility End-to-End.

When Behind, Leapfrog. "If we don't cannibalize ourselves, someone else will."

Put Products Before Profits. "My passion has been to build an enduring company where people were motivated to make great products. Everything else was secondary. Sure, it was great to make a profit, because that was what allowed you to make great products. But the products, not the profits, were the motivation."

Don't Be a Slave to Focus Groups. "Customers don't know what they want until we've shown them... Our task is to read things that are not yet on the page."

Bend Reality. "If it would save a person’s life, could you find a way to shave 10 seconds off the boot time? ... Don't be afraid."

Impute. "Focus, Empathize, Impute. People do judge a book by its cover."

Push for Perfection. "I want it to be as beautiful as possible, even if it’s inside the box. A great carpenter isn’t going to use lousy wood for the back of a cabinet, even though nobody’s going to see it... Real artists sign their work."

Tolerate Only "A" Players. "If something sucks, I tell people to their face. It’s my job to be honest... When you have really good people, you don’t have to baby them. By expecting them to do great things, you can get them to do great things. Ask any member of that Mac team. They will tell you it was worth the pain."

Engage Face-to-Face. "There’s a temptation in our networked age to think that ideas can be developed by e-mail and iChat. That’s crazy. Creativity comes from spontaneous meetings, from random discussions. You run into someone, you ask what they’re doing, you say ‘Wow,’ and soon you’re cooking up all sorts of ideas... If a building doesn’t encourage that, you’ll lose a lot of innovation and the magic that’s sparked by serendipity. So we designed the building to make people get out of their offices and mingle in the central atrium with people they might not otherwise see."

Know Both the Big Picture and the Details.

Combine the Humanities with the Sciences."I always thought of myself as a humanities person as a kid, but I liked electronics. Then I read something that one of my heroes, Edwin Land of Polaroid, said about the importance of people who could stand at the intersection of humanities and sciences, and I decided that’s what I wanted to do."

Stay Hungry, Stay Foolish. "Here’s to the crazy ones. The misfits. The rebels. The troublemakers. The round pegs in the square holes… While some see them as the crazy ones, we see genius. Because the people who are crazy enough to think they can change the world are the ones who do."