I think asshole in this context is quite harsh. All the interviews I've watched; all the articles I've read; he wanted the best for his company, his customers via his products and he wanted to push people to do their best work. Being difficult to work with, being pushed to to do your best work should NOT be misconstrued as being an asshole.
There are multiple accounts, including the recently published interview with Scott Forstall that he was a very carrying and generous person.
The respect he earned was for leading a company that produced great products and brought a company back from near bankruptcy to one of the biggest in the world. Not because people thought he was an asshole.