Remember the complaints raised in 1987 about Richard Attenborough’s “Cry Freedom,” the story of South African anti-apartheid activist Steve Biko (Denzel Washington), because the film put its focus not so much on Biko but on a progressive white newspaper editor Donald Woods (Kevin Kline), effectively telling the tale from his perspective? It was typical of a time when it was believed that narratives about Africa, in particular, needed to be relayed through the eyes of a Caucasian observer who could act as a western audience’s surrogate.

That time might be long past, but the storytelling device is resurrected, in a sort of reverse fashion (in that the African is a villain rather than a hero), in “The Last King of Scotland,” which recounts the reign of Ugandan dictator Idi Amin Dada (Forest Whitaker) from the viewpoint of a young Scot named Nicholas Garrigan (James McAvoy), who through a quirk of fate becomes his personal physician, confidant and close advisor. As it happens, Amin actually did have a Scottish doctor, but he was a far different sort of person than the young, adventure-seeking but peculiarly idealistic medic depicted here, who is the creation of novelist Giles Foden as filtered through the word-processors of scripters Peter Morgan and Jeremy Brock. Garrigan is in every significant respect a fictional character, a prism through which we’re given an imaginative glimpse of the charismatic but moody and dangerous dictator. The character’s not poorly drawn, and he’s played with relish by the energetic McAvoy, but he’s still unhistorical, and his presence means that one must understand that the particulars of the narrative are similarly undependable. One might as well take the Jack Burden of “All the King’s Men” as an authoritative source on Huey Long. And, as with “Freedom,” it’s still a tale of a white man’s redemption as a result of his African experience.

If you set aside those concerns, however, there’s a great deal that’s excellent about “The Last King of Scotland”–especially the ferociously vibrant performance of Whitaker. From the first frame he captures Amin’s combination of seductive charm and grotesque unpredictability, naivete and cunning, rude humor and implacable anger, to perfection. And, like Helen Mirren’s turn as Elizabeth II in “The Queen,” this one goes well beyond caricature to suggest the complexity of the person, although in this case the humanity is decidedly twisted. While Dr. Garrigan might be a a more lightweight fictional creation, moreover, McAvoy plays him quite well, making the character’s metamorphosis from boyish admirer to doubter and finally conscience-stricken conspirator more credible than it has any right to be. On the other hand, the important subplot that has him engage in an affair with one of the dictator’s wives (Kerry Washington) strains credulity to the breaking point; and its tragic denouement will go too far for many viewers, either in terms of melodramatic excess or because of the resultant carnage. (Generally speaking, the earlier portions of the picture work better than the last act. Bits that show the dictator’s taste for things Scottish and over-the-top entertainment are sure to draw laughs, but the satirical edge gets lost as the script grows darker and more ominous, with the closing segment–involving the plane highjacking that eventually led to the Israeli raid on Entebbe–and the final confrontation between Amin and Garrigan really taking things to an extreme.)

The supporting cast, though, is a solid one. Gillian Anderson shows up briefly as the wife of the clinic doctor with whom Garrigan intends to work before he’s summoned to the capital by Amin, and Simon McBurney oozes chicanery as the sort of foreign service officer whose motives are perpetually suspect. David Oyelowo is impressive as Amin’s former physician, as are the quietly effective Stephen Rwangyezi as a doomed Minister of Health as Abby Mukiibi as the dictator’s malevolent enforcer. Given what must have been difficult location conditions, Anthony Dod Mantle’s widescreen cinematography is good, although one might quarrel with the decision to give many of the images a ragged look, with almost bleeding colors. Alex Heffes’ score is just adequate.

In the final analysis, “The Last King of Scotland” is an uneven film that’s not entirely successful in juggling its very different tones. But even if the decision to tell the story from Garrigan’s perspective too often throws Amin off-stage, Whitaker’s performance as the unhinged dictator is so good that it makes the picture almost insanely watchable.