Will Smith has been nominated for this year's best actor Oscar
Being the iconic figure that he is, Ali still stirs up passionate debates among people who loved and loathed him.
Michael Mann's Ali, with Will Smith playing the title role, reportedly cost over £100m to make with both director and lead actor using their own money to finance some of the project.
Ali's boxing career lasted for more than 20 years, but Mann has decided to concentrate on the period between 1964 and 1974.
It was during that time that he won the world title, converted to the Muslim faith, refused to fight in the Vietnam war and lost his title before regaining it against George Foreman in Africa.
Condensing a life as large as Ali's into a 10-year period will no doubt upset some boxing purists, but the only other option would have been to make this a TV mini-series.
Having established the timescale, Mann works hard to ensure that little is left out.
The general public will be surprised to learn about how close Ali was to Malcolm X (Mario van Peebles), the cold-hearted way he treated his first two wives and his relationship with TV interviewer Howard Cosell (Jon Voight).
This film will also be judged by the quality and realism of the fight scenes - how well it rates against the legend that is Raging Bull.
Bearing in mind that Smith started from scratch as a fighter, his imitation of Ali in the ring is simply stunning.
With his opponents played by a variety of ex-champions and current contenders, the realism of each fight is captured with great authenticity.
One may presume that because key characters such as Foreman, Joe Frazier and Sonny Liston are played by boxers, the level of acting is not that high.
Nothing could be further from the truth - Ali features top level performances from the fighters as well as the supporting cast.
Despite all those endorsements, the film would amount to little if Smith's performance failed to do justice to the subject.
It is said that Ali believed that Smith was the only man capable of playing the part and on this evidence, the former champion is no mug.
The former star of the Fresh Prince of Bel Air delivers his finest ever performance on the big screen, coming as close as anyone could to capturing the charisma that made Ali The Greatest.
With so much to recommend itself about this film, it is a shame that director Mann could not keep his own contribution understated.
His insistence on having a thumping music score accompany 80% of the movie makes for some tiresome viewing.
While the trademark pop video style that he used in Miami Vice and Heat worked well, it really is not necessary here, where audiences expect only to find out about Ali.
Such a criticism seems minor in comparison to the breadth of achievement attempted in this film.
Ali aims, like the subject, to be The Greatest. It only just fails.
Ali opens in London on Friday 15 February and across the UK on 22 February