What a let-down (spoilers)
Based on the book? Hardly. Jesus this film was all over the place. It certainly wasn't a very accurate movie version of the book, and I think it suffered terribly as a result. It could (and should) have been a thrilling rollercoaster of an adventure story (as the book is) but the whole thing seemed uneven and rushed. Specifically....
The timeline was inaccurate and shonky as hell. Random examples - he's shown lying in bed with a pregnant Judy before faking his abduction when in reality he met her about a year after he went on the run (and he didn't fake his abduction from his parents' house either). Judy being extradited to America - never happened.
Massive chunks of the story missing - most heinously of all, the huge amount of time he spent in Hong Kong and Bangkok organising deals in the 1980s - it's one of the most interesting and entertaining sections of the book and was completely ignored.
Not even a mention of the dozens of aliases and disguises he went through while on the run.
Characters' dialogue interposed - are we really expected to believe his Pakistani connection spoke all the cockney actually spoken by Marks' cockney right-hand man (who was also never shown in the movie)?
No mention of Lord Moynihan, who befriended and then betrayed Marks to the DEA.
I'm surprised Marks himself professes to be happy with this film when Rose has taken such blatant liberties with his life story. It's a story that's been raked over in at least three books - it's not hard to get it right, surely?
In short, if you're a fan of Mr Nice (the book) prepare to be let down by Mr Nice (the movie). It's a crying shame that such a great true-life adventure story has been given such a terrible treatment.