Ashton Kutcher has revealed playing Apple's legendary co-founder Steve Jobs was an honour - but also terrifying - at the film's world premiere.
The biopic covers the 30 years from Jobs' teenage years to his time in charge of one of the most powerful and iconic technology brands across the globe.
jOBS was shown for the first time at the Sundance Festival in Utah, 15 months after the Apple boss died from pancreatic cancer at the age of 56.
At the premiere, 34-year-old Kutcher talked about his preparations to try and master Jobs' posture, hand gestures and eccentricities, saying his "painstaking research" included watching more than 100 hours of footage of the Apple innovator.
"To be playing a guy who so freshly is in people's minds, where everywhere you go you can run into people who met him or knew him or had seen a video of him... that's terrifying because everyone is an appropriate critic," Kutcher said.
"Everyone can tear you apart. Everyone can look at any detail, a piece of clothing or a speech pattern and go 'No, no, this is not what it was,' and that's really scary."
The film received applause from the audience, but it has not gone down as well with one of the people who worked most closely with Jobs.
Hours before the screening, Apple co-founder Steve Wozniak said the movie appeared to misrepresent aspects of his and Jobs' personalities and their early vision for the company.
Wozniak was commenting after seeing a brief clip of an early scene that was released online on Thursday.
"Totally wrong... The ideas of computers affecting society did not come from Jobs," Wozniak, who started Apple with Jobs and Ronald Wayne in a California garage in 1976, told technology blog Gizmodo.com.
Kutcher said he hoped Wozniak would look more kindly on the movie when he had seen the whole two hours.
"I hope that when he sees the film, he feels that he was portrayed accurately, that the film accurately represents who he was and how he was, and more importantly, inspires people to go and build things," he said.
jOBS is one of two films in production about Steve Jobs.
The other, based on Walter Isaacson's official biography Steve Jobs, is being developed by screen writer Aaron Sorkin of The West Wing and The Social Network fame.
Wozniak is known to be involved with the other film, although no release date or casting has been announced.