how do you know he wasn't a nice person in the first place, did you spend time with the guy?
nope, heard stories many times, some of them being told in the book mentioned above.
One of the most widely known was about the first iPod design process.
The goal was to make the world's smallest music player. Team worked their asses off to meet the readline. 2 days befire the date they showed Jobs a thin box, which, undoubtedly, was the smallest player by that time.
However, Steve was not satisfied. "It's too big", he said. The team said there was no way to make it smaller.
Then Jobs took the very first iPod in the history, worth millions of dollars of innovations and put it into the aquarium in his office. The team was close to losing conscience and stood horrified, looking at small air bulbs in the water.
"You see the air bulbs?", Steve Jobs said. "It means there was air in it. Empty space, which should be removed. Make it smaller"
And they made it smaller, and iPod was the beginning of a new era, just as many other Apple products we use daily.
That is why Steve Jobs was great. And that is why he was not "nice". He just devoted 100% of his effort to reach the goal and expected the same from his staff.